limit number of /subscribe clients and queries per client (#3269)

* limit number of /subscribe clients and queries per client

Add the following config variables (under [rpc] section):
  * max_subscription_clients
  * max_subscriptions_per_client
  * timeout_broadcast_tx_commit

Fixes #2826

new HTTPClient interface for subscriptions

finalize HTTPClient events interface

remove EventSubscriber

fix data race

```
WARNING: DATA RACE
Read at 0x00c000a36060 by goroutine 129:
  github.com/tendermint/tendermint/rpc/client.(*Local).Subscribe.func1()
      /go/src/github.com/tendermint/tendermint/rpc/client/localclient.go:168 +0x1f0

Previous write at 0x00c000a36060 by goroutine 132:
  github.com/tendermint/tendermint/rpc/client.(*Local).Subscribe()
      /go/src/github.com/tendermint/tendermint/rpc/client/localclient.go:191 +0x4e0
  github.com/tendermint/tendermint/rpc/client.WaitForOneEvent()
      /go/src/github.com/tendermint/tendermint/rpc/client/helpers.go:64 +0x178
  github.com/tendermint/tendermint/rpc/client_test.TestTxEventsSentWithBroadcastTxSync.func1()
      /go/src/github.com/tendermint/tendermint/rpc/client/event_test.go:139 +0x298
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:827 +0x162

Goroutine 129 (running) created at:
  github.com/tendermint/tendermint/rpc/client.(*Local).Subscribe()
      /go/src/github.com/tendermint/tendermint/rpc/client/localclient.go:164 +0x4b7
  github.com/tendermint/tendermint/rpc/client.WaitForOneEvent()
      /go/src/github.com/tendermint/tendermint/rpc/client/helpers.go:64 +0x178
  github.com/tendermint/tendermint/rpc/client_test.TestTxEventsSentWithBroadcastTxSync.func1()
      /go/src/github.com/tendermint/tendermint/rpc/client/event_test.go:139 +0x298
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:827 +0x162

Goroutine 132 (running) created at:
  testing.(*T).Run()
      /usr/local/go/src/testing/testing.go:878 +0x659
  github.com/tendermint/tendermint/rpc/client_test.TestTxEventsSentWithBroadcastTxSync()
      /go/src/github.com/tendermint/tendermint/rpc/client/event_test.go:119 +0x186
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:827 +0x162
==================
```

lite client works (tested manually)

godoc comments

httpclient: do not close the out channel

use TimeoutBroadcastTxCommit

no timeout for unsubscribe

but 1s Local (5s HTTP) timeout for resubscribe

format code

change Subscribe#out cap to 1

and replace config vars with RPCConfig

TimeoutBroadcastTxCommit can't be greater than rpcserver.WriteTimeout

rpc: Context as first parameter to all functions

reformat code

fixes after my own review

fixes after Ethan's review

add test stubs

fix config.toml

* fixes after manual testing

- rpc: do not recommend to use BroadcastTxCommit because it's slow and wastes
Tendermint resources (pubsub)
- rpc: better error in Subscribe and BroadcastTxCommit
- HTTPClient: do not resubscribe if err = ErrAlreadySubscribed

* fixes after Ismail's review

* Update rpc/grpc/grpc_test.go

Co-Authored-By: melekes <anton.kalyaev@gmail.com>

rpc/client/mock/client.go

@@ -21,6 +21,7 @@ import (
 	"github.com/tendermint/tendermint/rpc/client"
 	"github.com/tendermint/tendermint/rpc/core"
 	ctypes "github.com/tendermint/tendermint/rpc/core/types"
+	rpctypes "github.com/tendermint/tendermint/rpc/lib/types"
 	"github.com/tendermint/tendermint/types"
 )
 
@@ -76,11 +77,11 @@ func (c Call) GetResponse(args interface{}) (interface{}, error) {
 }
 
 func (c Client) Status() (*ctypes.ResultStatus, error) {
-	return core.Status()
+	return core.Status(&rpctypes.Context{})
 }
 
 func (c Client) ABCIInfo() (*ctypes.ResultABCIInfo, error) {
-	return core.ABCIInfo()
+	return core.ABCIInfo(&rpctypes.Context{})
 }
 
 func (c Client) ABCIQuery(path string, data cmn.HexBytes) (*ctypes.ResultABCIQuery, error) {
@@ -88,49 +89,49 @@ func (c Client) ABCIQuery(path string, data cmn.HexBytes) (*ctypes.ResultABCIQue
 }
 
 func (c Client) ABCIQueryWithOptions(path string, data cmn.HexBytes, opts client.ABCIQueryOptions) (*ctypes.ResultABCIQuery, error) {
-	return core.ABCIQuery(path, data, opts.Height, opts.Prove)
+	return core.ABCIQuery(&rpctypes.Context{}, path, data, opts.Height, opts.Prove)
 }
 
 func (c Client) BroadcastTxCommit(tx types.Tx) (*ctypes.ResultBroadcastTxCommit, error) {
-	return core.BroadcastTxCommit(tx)
+	return core.BroadcastTxCommit(&rpctypes.Context{}, tx)
 }
 
 func (c Client) BroadcastTxAsync(tx types.Tx) (*ctypes.ResultBroadcastTx, error) {
-	return core.BroadcastTxAsync(tx)
+	return core.BroadcastTxAsync(&rpctypes.Context{}, tx)
 }
 
 func (c Client) BroadcastTxSync(tx types.Tx) (*ctypes.ResultBroadcastTx, error) {
-	return core.BroadcastTxSync(tx)
+	return core.BroadcastTxSync(&rpctypes.Context{}, tx)
 }
 
 func (c Client) NetInfo() (*ctypes.ResultNetInfo, error) {
-	return core.NetInfo()
+	return core.NetInfo(&rpctypes.Context{})
 }
 
 func (c Client) DialSeeds(seeds []string) (*ctypes.ResultDialSeeds, error) {
-	return core.UnsafeDialSeeds(seeds)
+	return core.UnsafeDialSeeds(&rpctypes.Context{}, seeds)
 }
 
 func (c Client) DialPeers(peers []string, persistent bool) (*ctypes.ResultDialPeers, error) {
-	return core.UnsafeDialPeers(peers, persistent)
+	return core.UnsafeDialPeers(&rpctypes.Context{}, peers, persistent)
 }
 
 func (c Client) BlockchainInfo(minHeight, maxHeight int64) (*ctypes.ResultBlockchainInfo, error) {
-	return core.BlockchainInfo(minHeight, maxHeight)
+	return core.BlockchainInfo(&rpctypes.Context{}, minHeight, maxHeight)
 }
 
 func (c Client) Genesis() (*ctypes.ResultGenesis, error) {
-	return core.Genesis()
+	return core.Genesis(&rpctypes.Context{})
 }
 
 func (c Client) Block(height *int64) (*ctypes.ResultBlock, error) {
-	return core.Block(height)
+	return core.Block(&rpctypes.Context{}, height)
 }
 
 func (c Client) Commit(height *int64) (*ctypes.ResultCommit, error) {
-	return core.Commit(height)
+	return core.Commit(&rpctypes.Context{}, height)
 }
 
 func (c Client) Validators(height *int64) (*ctypes.ResultValidators, error) {
-	return core.Validators(height)
+	return core.Validators(&rpctypes.Context{}, height)
 }