Port to mapping-io (Glitch's Version)

[TheGlitch76]

This is step 0 in adding the ability for Loader to use alternative intermediates for mods, or use something like mojmaps at runtime. This PR migrates the pre-existing MappingConfiguration to use mapping-io, but doesn't do much to actually refactor Loader to take advantage of mapping-io's strengths.

This PR moves a few dependencies to be shadowed that Floader moved as well. Tiny Remapper was required to be moved to work with mapping-io, tiny mapping parser was removed by upstream, and I just decided to bring AccessWidener in line with upstream as well.

(PS: I know QMT exists-ish, but it's not finished and I want to work on a modloader, not a mappings parser. When and if QMT is finished, we can evaluate migrating to it, but the potential to use a first-party library later shouldn't prevent us from improving Loader today)