Draft: testing/osu-lazer: new aport

Current TODO:

• Split librealm-wrapper into separate package
• Split libstbi into into separate package
• Add desktop icon and other eye-candy that the AUR package provides
• Package libbass instead of relying on the prebuilt one (turns out it's non-free and there is no source code, so this is pretty counterintuitive)
• Verify that the dependencies I added are enough
• Fix the missing libasound2-dev warning on startup (caused by lack of alsa-lib-dev and unloaded snd_seq module; added post-install note for the latter)

Can verify that it starts up on my system, and beatmaps play quite fine (although it seems that i'd have to tweak the offsets...)

cc @psykose @ayakael