feat(ci)!: complete workflows revamp

[xarvex]

Summary

Implements: #1030 (partially, doesn't create a GitHub Release yet)
Fixes: #1406 (macos-15-intel has to be used now)

Notable Changes

• Some external actions have been removed to prefer local tools.
• setup-uv has been added to benefit from uv's cache and lightweight installation.
• Single local action for all Python setups, which can take a 'group' argument for extra tools to be installed. This removes the duplicated (and sometimes diverging) setup processes.
• Multi-platform jobs are no longer split up into multiple jobs, but rather take a matrix of runners, with each step checking the OS if relevant. This, as well, avoids duplication of work.
• Steps have been made parallelized thanks to a recent GitHub change.
• Nightly builds are now made, albeit without releases. The artifacts will, for now, be available on the action artifacts page.

Future Work

The flow of releases still needs to be expanded on, the idea being that the action can be the entry point for creating a new release, be it Nightly, Pre-Release, or full Release. Nightlies will need some concept of cleanup to ensure there won't be many of those piling up. While working on this, #1282 is being taken into consideration.

As well, more checks might want to be added, such as for #892.

Tasks Completed

• Platforms Tested:
  • Windows x86
  • Windows ARM
  • macOS x86
  • macOS ARM
  • Linux x86
  • Linux ARM
• Tested For:
  • Basic functionality
  • PyInstaller executable