p2p: make persistent prop independent of conn direction (tendermint#3593

)

## 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 tendermint#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 tendermint#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 <[email protected]>

* fix merge conflict

* remove sleep from TestPEXReactorDoesNotDisconnectFromPersistentPeerInSeedMode

We don't need it actually.

rpc/core/net.go

@@ -204,6 +204,8 @@ func UnsafeDialPeers(ctx *rpctypes.Context, peers []string, persistent bool) (*c
 	if err := p2pPeers.DialPeersAsync(peers); err != nil {
 		return &ctypes.ResultDialPeers{}, err
 	}
+	// parsing errors are handled above by AddPersistentPeers
+	_ = p2pPeers.DialPeersAsync(peers)
 	return &ctypes.ResultDialPeers{Log: "Dialing peers in progress. See /net_info for details"}, nil
 }