fix: correctly handle pg_try_advisory_lock

[levkk]

Problem

We assumed all calls to pg_try_advisory_lock were successful and pinned the client.

Solution

Parse the result we receive from Postgres and only record the advisory lock as acquired if the function call returns true.

fixes #1578

Clean up

• Cleanup the mess in process_server_message a bit
• Move advisory lock parsing and its tests into its own module in the parser

[codecov]

Codecov Report

❌ Patch coverage is 96.97987% with 27 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...og/src/frontend/router/parser/advisory_lock/mod.rs	94.11%	12 Missing ⚠️
pgdog/src/frontend/client/query_engine/query.rs	84.50%	11 Missing ⚠️
pgdog/src/frontend/client/query_engine/lock.rs	88.46%	3 Missing ⚠️
...g/src/frontend/router/parser/advisory_lock/test.rs	99.78%	1 Missing ⚠️

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