Clean up build.cmd/build-test.cmd/runtest.cmd

Clean up build.cmd/build-test.cmd/runtest.cmd

Various minor cleanups:
1. Use the same naming/style for all three.
2. Make the style consistent throughout each. E.g., consistent indents,
   capitalization.
3. Add more consistent output, including the prefix tag used everywhere.
4. build.cmd: only build cross components if native build is enabled.
5. Use new __Logging variable to consolidate all logging arguments,
   to reduce large (unexpanded) command line lengths.

Commit migrated from https://github.com/dotnet/coreclr/commit/a248d79b29f7c8f6858248a3b1661a6795d6ce19