feat: impl some "set"s to adapt to some client apps

[MichaelScofield]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

What's changed and what's your intention?

The "set"s are:

• ignored:
  • set bytea_output and set datestyle (both have issues tracked) from pg
  • set profiling from mysql. It's not something we will impl (rather we may prefer tracing instead). Plus it's deprecated. See here
• validated:
  • set client_encoding from pg. Must be "utf8" because it's universal and sufficient, and we don't bother to convert bytes around.

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

[codecov]

Codecov Report

Attention: Patch coverage is 4.00000% with 24 lines in your changes are missing coverage. Please review.

Project coverage is 85.08%. Comparing base (c52bc61) to head (e878854).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3443      +/-   ##
==========================================
- Coverage   85.44%   85.08%   -0.37%     
==========================================
  Files         895      895              
  Lines      147093   147118      +25     
==========================================
- Hits       125685   125170     -515     
- Misses      21408    21948     +540     

[fengjiachun]

LGTM

[tisonkun]

Thank you!