Move post-install scripts that contain openrc-specific commands to openrc subpackages

Closes #3045 (closed)

This MR moves all post-install files that contain openrc-specific configs or commands to their respective subpackage. This is required for said packages to be installed properly on a systemd-based system. Otherwise, APK will error on the install.

When systemd is merged these packages will need to have a respective systemd subpackage as well so they can still function as expected.

Todo:

• Finish moving testing scripts.
• Modify nonfree-firmware and certain kernel packages to not automatically install with openrc. (Maybe keep the original subpackage but use install_if="$pkgname-nonfree-firmware=$pkgver-r$pkgrel openrc with the openrc subpackages?)