[PP-2] Enable dynamic queries to produce SQL with positional placeholders

Merged MR with 📌 Create the database driver for MySQLi for async queries Active to allow progressing.

While it's relatively straightforward to do this for plain INSERTs, this get complicated for all other operations where conditions get into the equation. The problem is that named placeholders are allowed in the expressions' string: while we could easily parse the strings to replace them with positional ones, that would defy the purpose of this issue that is to natively build SQL with positional placeholders, without need of reprocessing.

I start thinking we need something along the lines of 📌 [WIP] Decouple identifier management from database Connection, introduce an IdentifierHandler class Postponed , but for placeholders. So to have placeholders as value objects and not strings and therefore being able to build SQL taking that into account.