Implement Thai language support with combining character handling

[Faelayis]

issues: ppy/osu#21429

This pr introduces locale-aware handling of combining characters in text rendering, with a particular focus on Thai language support. The changes add a new CombiningCharacter configuration class, update text builder classes to accept and use this configuration, and ensure that combining marks (such as those used in Thai script) are stacked and positioned correctly. The configuration is automatically applied based on the current locale.

Before master

After fix/font-combining

[bdach]

I have zero interest in merging this, this is basically attempting to start a complete new text shaping library within framework. We don't have the scope and resources for that. Next we know a Vietnamese user will come here and start complaining that Vietnamese combining characters are incorrect.

In my eyes an actual scalable solution to this would to just do what everyone else is doing and incorporate harfbuzz or equivalent. Potentially combined with #6665.

Maybe some other maintainer will bite.

[smoogipoo]

I agree with the above, and I'm pretty sure SDL_ttf uses harfbuzz. Have suggested the library to be used in #6665.

Thanks for the contribution, but let's not do it this way.