## Description
Previously only outbound peers can be persistent.
Now, even if the peer is inbound, if it's marked as persistent, when/if conn is lost,
Tendermint will try to reconnect. This part is actually optional and can be reverted.
Plus, seed won't disconnect from inbound peer if it's marked as
persistent. Fixes#3362
## Commits
* make persistent prop independent of conn direction
Previously only outbound peers can be persistent. Now, even if the peer
is inbound, if it's marked as persistent, when/if conn is lost,
Tendermint will try to reconnect.
Plus, seed won't disconnect from inbound peer if it's marked as
persistent. Fixes#3362
* fix TestPEXReactorDialPeer test
* add a changelog entry
* update changelog
* add two tests
* reformat code
* test UnsafeDialPeers and UnsafeDialSeeds
* add TestSwitchDialPeersAsync
* spec: update p2p/config spec
* fixes after Ismail's review
* Apply suggestions from code review
Co-Authored-By: melekes <anton.kalyaev@gmail.com>
* fix merge conflict
* remove sleep from TestPEXReactorDoesNotDisconnectFromPersistentPeerInSeedMode
We don't need it actually.
