Use $schema keys for menuinst JSON validation

[jaimergp]

Description

Recent changes in menuinst fixed this design issue. We can now safely rely on $schema to self-validate the JSON document. As a result, menuinst is no longer necessary as a dependency either.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[jaimergp]

@conda/builds-tools, this is ready for review! 🙏 See conda/menuinst#283 for broader context.

[jaimergp]

Shall we restrict which domains can be provided so they can only come from a series of pre-approved locations? e.g. github.com/conda/menuinst, schemas.conda.org, etc. Otherwise users might be able to simply link the equivalent of "allow-everything" schema and bypass these validations. Not that they result in errors, though.

[codspeed-hq]

CodSpeed Performance Report

Merging #5569 will not alter performance

_{Comparing jaimergp:menuinst-230 (80caf05) with main (9da6306)}

Summary

✅ 5 untouched benchmarks