[chore] SQL Prepared Statements

[zach2good]

• I have paid attention to this example and will edit again if need be to not break the formatting, or I will be ignored
• I have searched existing issues to see if the issue has already been opened
• I have checked the commit log to see if the issue has been resolved since my server was last updated
• I have read the Contributing Guide
• I have specified what branch this happens on branch: EDITME

Additional Information (Steps to reproduce/Expected behavior) :

They're not very hard to use, we could be using them:
https://gist.github.com/henryscala/f7a18fbb36fdd17351046fdce7c64c01

• Register on startup
• Bind and use
• They release themselves on connection death/shutdown

Will need to measure to see if it makes much/any difference

[zach2good]

I snuck a partial/unworking implmentation in during my last SQL refactor. Still need to make some utilities for easy binding of params and results:
https://github.com/LandSandBoat/server/blob/base/src/common/sql_prepared_stmt.cpp

I feel like if it's extremely fiddly and hard to set these up, then nobody will ever consider using them. So I'll make sure there's sufficient tooling.

[zach2good]

API:
https://github.com/LandSandBoat/server/blob/base/src/common/sql.cpp#L597-L611

[zach2good]

How I'm imagining they're used:

auto res = sql-> GetPreparedStatement("GET_CHAR_VAR")(params...);

[zach2good]

It's in, as part of: #4601