Add experimental Raspberry Pi support

[kkebo]

closes #4827, closes #2574, closes #6546

I added experimental Raspberry Pi support to UTM. Localization strings are translated by an LLM, so they may contain mistranslations.

Changes:

• Added support for using the Raspberry Pi board's built-in framebuffer as a display
• Removed default PCI devices from raspi* machines by default to avoid crashes
• Added support for each machine constrained to fixed-size memory to avoid crashes

Test:

I verified that my hobby OS for Raspberry Pi 4 could boot with raspi4b.

#4827 (comment)

Known issues, likely existing issues caused by a race condition in UTM event handling:

• (iOS) The initial framebuffer contents randomly fail to appear. (likely because the first frame is rendered before the GL context is fully initialized)
• (iOS) Serial output generated before the GUI terminal is opened is not displayed.
• (macOS) Serial output is not displayed if one or more display devices are attached.

[kkebo]

The PR is now ready for reviewing.