Consolidate solution files into one single solution file. Add solution files in place of old solutions

[Arthri]

• Merged all solution files(OTAPI.Mods.sln, OTAPI.Client.Launcher.sln, and OTAPI.Server.Launcher.sln) into one single solution(OTAPI.sln)
• Added solution filters in place of old solution files(OTAPI.Mods.slnf, OTAPI.Client.Launcher.slnf, and OTAPI.Server.Launcher.slnf)
• Set platform for OTAPI.Client.Launcher and OTAPI.Scripts to Any CPU

Solution filters only contain paths to projects, and not if or how to build them, which helps reduce the amount of configuration and desynchronization that can happen with multiple solutions.

[SignatureBeef]

nice, seems to work on windows at least...can't recall what x64 was used for but the less shenanigans the better. at some point doco needs to be updated to match this now as well, but also i see it needs updating from net5 too.