feat!: limit protocol streams per-connection (#1255)

* feat: limit protocol streams per-connection

Uses the `maxInboundStreams` and `maxOutboundStreams` of the `registrar.handle`
opts to limit the number of concurrent streams open on each connection
on a per-protocol basis.

Both values default to 1 so some tuning will be necessary to set
appropriate values for some protocols.

* chore: make error codes consistent

* chore: fix up examples

test/content-routing/dht/operation.node.ts

@@ -73,9 +73,9 @@ describe('DHT subsystem operates correctly', () => {
     })
 
     it('should get notified of connected peers on dial', async () => {
-      const connection = await libp2p.dialProtocol(remAddr, subsystemMulticodecs)
+      const stream = await libp2p.dialProtocol(remAddr, subsystemMulticodecs)
 
-      expect(connection).to.exist()
+      expect(stream).to.exist()
 
       return await Promise.all([
         pWaitFor(() => libp2p.dht.lan.routingTable.size === 1),