[network] Refactor PeerManager handle new connection
[network] Refactor PeerManager handle new connection

To separate the logic between `Inbound` and `Outbound` I refactored it
to be cleaner, and not have 3 places to check for the direction of the
connection

Closes: #7518

libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core