Adding nvchecker conf, listing most (or all) optional package dependencies and fixed license identifier

[Torxed]

This PR mainly aims to conform with Arch's best practices surrounding PKGBUILD's.

• Adding check() hook for future test suit - https://wiki.archlinux.org/title/Creating_packages#check()
• Converted license def to match SPDX - https://wiki.archlinux.org/title/PKGBUILD#license
• Added most if not all packages we used as optdepends as they are optional dependencies and used when the user selects a relevant profile. This should be a good step for future fail-safe's regarding package name changes etc. As we can cross-reference from other packages back to archinstall when we change other packages.

[Torxed]

Generally I am wondering why these files live in here at all and why this has not been a merge request towards the package repository instead:

It's because:

git clone https://github.com/archlinux/archinstall.git
cd archinstall
makepkg -s

To get the latest code for testing, we have archinstall-git option too but this was added way back before that existed as an option.