Use rcodesign for dylib signing where avaiilable and clear out all "._" files...

• Use rcodesign for dylib signing where avaiilable for building on Linux
• Clear out all "._" files before building in order to support building on external hard drive not formatted with APFS when building on MACOS

NOTE: When attempting to run the build for the headless version I get the following error which seems unrelated, so I was unable to test the MACOS headless build:

/GitHub/Ryujinx/src/Ryujinx.Headless.SDL2/Ryujinx.Headless.SDL2.csproj : error NU1010: The PackageReference items Ryujinx.Graphics.Nvdec.Dependencies do not have corresponding PackageVersion.

Restore failed with 1 error(s) and 2 warning(s) in 1.0s