feat: add SQLite3 config synchronous

[michalsn]

Description
This PR adds support for the synchronous setting in SQLite3. It's not persistent across connections, which means it resets to the default (usually 2) with every new connection. We must set synchronous on each connection if we want it to differ from the default.

More info about this setting: https://www.sqlite.org/pragma.html#pragma_synchronous

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[maniaba]

It might be a good idea to add validation or throw a database exception in this section. Since we are directly passing $this->synchronous into the PRAGMA statement, without validating whether the value is one of the expected integers (0, 1, 2, 3), we risk unexpected behavior or incorrect PRAGMA settings if an invalid value is provided. Adding validation would ensure we are handling only valid inputs and would prevent potential silent failures.

Additionally, it might be worth considering the use of an enum to define the valid values for synchronous. This would provide a clearer and more structured way to enforce the allowed options and make the code easier to maintain.

[michalsn]

I added synchronous value validation and test.

I think using an enum here would mess with simplicity a bit - but if more people say we should go this way I can add it. Although I don't think we have a single enum in the project at the moment (I might have missed something).

[datamweb]

I don't think using an enum is necessary in this case. The reason enums weren't used in the framework was due to older PHP versions, but I believe we should use enums where possible.

In general, I'm a fan of enums as they improve code readability, but I don't see a strong need for them here.