Combine SDL and Qt frontends under a single executable

[OpenSauce04]

Closes #497

This pull request will reimplement the previously removed SDL frontend by taking both it and the Qt frontend and making them both accessible within a single program using command line options.

Each of the two frontends can be selectively compiled if the user wishes to do so, the same as was possible when they were separate executables.

• The Qt frontend is used by default, and the SDL frontend is accessed using the -n command line option (short for no-gui).
• If the Qt frontend is not compiled, the SDL frontend is instead always used.

[OpenSauce04]

Keep in mind that the code here is super unfinished, I'm just creating this PR to make development progress more visible as this will take a while to finish.

[OpenSauce04]

The majority of license warnings will be ignored due to most changes coming from a simple change in file path or a re-introduction of previously removed code

[OpenSauce04]

Pre-review todo list (roughly in-order, subject to addition):

• [x] Make command line option behaviour between both SDL and Qt frontends interchangeable
  • [x] lime_qt: Implement long option names
  • [x] lime_qt: Implement --movie-record-author option
  • [x] lime_qt: Add a message for --multiplayer stating a lack of implementation
  • [x] lime_sdl: Make --windowed option valid in lime_sdl
• [x] Deduplicate help string
• [x] lime_qt: Fix Qt resources in dist/ not loading correctly
• [x] lime_sdl: Make command-line text output appear in a text box on Windows (see https://github.com/Lime3DS/Lime3DS/pull/481#issuecomment-2397985631 for context)
• [x] lime_sdl: Check that there are no missing ReadSetting calls for config options never added to the SDL frontend
• [x] Fix build issues
• [x] Self-review code to pick up easy corrections that need to be made
• [x] Update license headers where appropriate

[OpenSauce04]

Testing checklist (both frontends):

• [x] Linux (AppImage)
• [x] Linux (Flatpak)
• [x] Windows MSVC
• [x] Windows MSYS2
• [x] MacOS (x86)
• [x] MacOS (ARM)

[OpenSauce04]

Merged in 563089d792296ccc5196da8033a0f52344347455 and da2912e75fd841cc0397458b6a3be80c41ffe151