Get rid of amazon properties dependency in library builder

It's convenient for situations where the configuration already exists, but when you want to introduce a newly built library or version, you really don't want to have to commit something to CE master.

These lines are to blame:
https://github.com/compiler-explorer/infra/blob/a203197ee301f486bb45c6f005afb30c00a2d737/bin/lib/library_builder.py#L73

The static/shared lib names are needed so that the build process can look up the binaries and conclude whether or not it built successfully:
https://github.com/compiler-explorer/infra/blob/master/bin/lib/library_builder.py#L328

(Note that lib names can change between versions.)

Ideally, introduce some YAML variables that make the same possible even when not found in the amazon properties.

Don't think we can use the `make_targets` variable for this since make commands can and probably won't match the library names.