[Code] Add mysql prepared statement support

[hgtw]

Description

This adds support for using prepared statements for MySQL queries. It is intended for use in a database quest API but it can be used in source with some caveats:

• It uses exceptions for error handling instead of returning a fake result that needs checked. Usage must be wrapped in try/catch.

• DBcore has a connection mutex which indicates the connection might be shared with other threads. This mutex is locked for certain stmt operations in an attempt to make it safe to use with multi threaded connections.

• Prepared statements should only be used on the main thread since the internal logging is not synchronized.

• Unlike the current query API which retrieves all results as strings, results are stored in buffers that represent the db field type. Getter functions are available to retrieve values as desired types.

Documentation will be added after it's merged, but an example of usage in C++

#include <../common/mysql_stmt.h>

void foo()
{
  try
  {
    mysql::PreparedStmt stmt = content_db.Prepare("select * from spells_new where id = ? or Name = ?");
    mysql::StmtResult result = stmt.Execute({ 100, "Illusion: Feir'Dal" });
    int total_rows = result.RowCount();
    while (mysql::StmtRow row = stmt.Fetch())
    {
      int32_t id = *row.Get<int32_t>(0); // get id by col index, we know this can't be NULL so dereference
      std::string name = row["name"].value_or(""); // get str by field name, value may be NULL
    }
  }
  catch (const std::exception& ex)
  {
    // handle failure, the error is already logged with LogMySQLError
  }
}

Checklist

• I have tested my changes
• I have performed a self-review of my code. Ensuring variables, functions and methods are named in a human-readable way, comments are added only where naming of variables, functions and methods can't give enough context.
• I have made corresponding changes to the documentation (if applicable, if not delete this line)
• I own the changes of my code and take responsibility for the potential issues that occur
• If my changes make database schema changes, I have tested the changes on a local database (attach image). Updated version.h CURRENT_BINARY_DATABASE_VERSION to the new version. (Delete this if not applicable)