Support for the PG wire protocol

[mamcx]

Description of Changes

Closes #2686.

Add support for listening using the PG wire protocol so pg clients could be used against the database.

API and ABI breaking changes

None.

Expected complexity level and risk

2

There is open questions that are in the ticket #2686. Also the crate used here require RustTls, so it could be good idea to decide if:

• Rewrite a big chunk of code to use OpenSSL
• Move to RustTls Remove openssl #1700
• Pay for the extra compilation cost.

I open another port(5433) to listen for pg connections using ssl. Need to be decided if this is the way or instead try to multi-plex the current port for both protocols.

Testing

Only manual testing so far. Solving the above questions allow me to implement some unit tests. Also, not yet integrated into cloud for the same reasons.