main/raspberrypi: rename with userland and modernise

Hi @fabled
A few suggestions about that package:

• naming: how about renaming it raspberrypi-userland to really relate to its origin, and be clearer and consistent with other rpi related Alpine packages?
• move binary utilities into /usr/bin rather than keeping them in /opt/vc/bin as in libraspberrypi-bin: will make use more straightforward with no $PATH adjustment (alternative could be to symlink into main apps from /usr/bin).
• add udev rules like KERNEL=="vchiq", GROUP="video", MODE="0660" & al, as in libraspberrypi0 PiOS package, or Fedora's instance.

As a side note, rebuilding the package recently I incidentally found-out resulting /opt/vc/bin does not contain any of the containers* binaries... Though no particular interest on them, I'm surprised current Alpine repos (3.x, Edge) have them there, while other distros don't... Not sure what's going-on with build process since I'm using same APKBUILD...

Appreciate any feedback, Thanks!