Adds option to log which parameter status is changed by the client

[zainkabani]

This PR helps to debug what kind of parameters are being set by the client outside of the startup. This will only log for SET statements that respond with a ParameterStatus packet

set application_name to 'name';

will return a parameter status but

set statement_timeout to 10;

will not return a parameter status and will not be logged

[levkk]

I feel like you want to almost log all SET statements outside of startup because they are all pretty much considered application bugs by the Postgres community, outside of special circumstances. e.g. changing statement_timeout on a production database is a problem, because one client basically allows itself to take up a lot of resources, probably against the wishes of the DBA.

What do you think?

[zainkabani]

I'd love to have that visibility too, the issue is that the SET statements come in as queries so we'd have to parse those. For every set statement a SET command tag is returned with no other data. For a subset of SETs (ie. application_name) we also get back a parameter status packet, which gives you the key and value of the parameter. So unless we parse every query this is the only way we can get what the client is setting.

[levkk]

LGTM.