Remove chip features from xtensa-lx package, add a super simple CI workflow

[jessebraham]

• Removes the chip features from xtensa-lx, as they are no longer needed; the spin feature replaces them, which is used with the ESP32 and ESP32-S3.
• Add rustfmt config file, format packages (sorry for the noise)
• Add a super simple CI workflow to check formatting and build packages__*__
  • I'm getting some weird error trying to build xtensa-lx-rt using GHA for whatever reason. I've disabled these checks for now, and will get them working in my next PR (as I plan to remove core-isa-parser, the source of our issues (I think) ).

[MabezDev]

Thanks! LGTM