chore(developer): cleanup -- remove legacy kmp.inf, kps fields

For 19.0, I think we can stop writing kmp.inf altogether in the compiler -- kmp.json has been supported since 2017. We still need to support reading it as there are many legacy packages which have not been updated to kmp.json and some of which probably will never be updated.

In the Delphi code, it may be worth splitting the kmp.json/kmp.inf reading from the kps reading/writing as they are two different, albeit related, formats. It would make future updates simpler if the formats weren't tied together.

Also:

1. Remove kmp.inf writer, kmp.json writer from Delphi code (need kmp.inf reader and kmp.json reader for Windows)
2. Remove CopyLocation, Description fields from kps.File, kmp.File throughout the codebase (test that downlevel Keyman doesn't depend on presence of those fields in kmp.json; if it does, then write static values)
3. Document all remaining fields in .kps format.