Fix Arabic RTL layout and shaping in Cairo UI rendering

[SaudMD]

Summary

This PR improves Arabic UI rendering in the Cairo text pipeline.

Arabic text was previously shown with disconnected letters, incorrect right-to-left ordering, and inconsistent mixed Arabic/Latin layout in several client UI screens. This change adds contextual Arabic shaping and visual RTL preparation before text measurement and drawing, then routes the relevant UI rendering paths through that logic.

What Changed

• Added ComplexTextLayout to prepare RTL text before rendering.
• Added contextual Arabic shaping based on the original logical characters, so medial/final joining stays correct.
• Added lam-alef ligature handling for لا, لأ, لإ, and لآ.
• Added mixed-direction visual reordering with mirrored bracket handling for RTL runs.
• Routed Cairo text measurement and drawing through the same prepared-text path.
• Added an RTL-aware font fallback path in CairoFont.
• Added CairoGlyphLayout as an optional native glyph path, but kept it disabled because the current runtime resolves glyph indices without performing Arabic shaping correctly.
• Updated horizontal and vertical tab controls to measure/draw tab labels using the same RTL-aware font setup.

Files

• Client/UI/ComplexTextLayout.cs
• Client/UI/CairoFont.cs
• Client/UI/CairoGlyphLayout.cs
• Client/UI/TextDrawUtil.cs
• Client/UI/TextTextureUtil.cs
• Client/UI/Elements/Impl/Interactive/Controls/GuiElementHorizontalTabs.cs
• Client/UI/Elements/Impl/Interactive/Controls/GuiElementVerticalTabs.cs

Testing

Tested on Windows with the built VintagestoryAPI.dll installed into the game.

Verified manually in:

• Main menu
• World creation screen
• Loading/status text
• Book/tutorial UI
• Mixed Arabic/Latin cases such as parentheses and version-like text

Confirmed outcomes:

• No world-load crash after removing the temporary test mod
• Arabic strings are rendered right-to-left
• Contextual letter joining is corrected
• Missing-glyph boxes disappeared after switching the RTL fallback away from Simplified Arabic in the tested Windows setup

Notes

• Translation cleanup in the external Arabic mod was kept separate and is not part of this PR.
• The current fallback font choice was validated on Windows. Maintainers may prefer to replace it with a platform-specific or configurable Arabic-capable fallback for non-Windows environments.

[pizza2004]

Hello! Sorry about the delay in looking at this, things have been busy lately. Is it possible to show a before and after of what the changes look like from this?