[feature request] Allow frzr to update initramfs to support device-quirks

[alkazar]

Some device-quirks scripts require updating the initramfs with additional firmware or other files.

In order to support this use case we could do the following:

• create a new command, frzr-initramfs, which should rebuild all installed initramfs images
• need some way for device-quirks to specify which files need to be added, some options:
  - just use /etc/mkinitcpio.conf
  - copy or link files under /etc/frzr.d/initramfs/
• frzr-deploy needs to run frzr-initramfs after an update
• frzr-initramfs should only update the initramfs IF there are files that need to be added, so need some way to be able determine that

[ruineka]

This will also be useful for adding resume for hibernation.