Release 1.2.0 still has GitHub Rest API remnants

[VisLab]

The new manifest (schema_versions.json) provided in hed-schemas allows schema retrieval from GitHub to be done with CDN rather than REST API. These should be removed in the next minor release.

[viranovskaya]

Hi, I traced the remaining GitHub REST paths.

A complete removal would cover the REST URL constants, token handling, directory traversal helpers, and the REST-specific arguments in cache_xml_versions() and get_available_hed_versions(). Version listing, bulk caching, and on-demand downloads would then all use schema_versions.json.

I have a local implementation with tests for released and prerelease versions, cache population, on-demand downloads, ETag reuse, and network failures.

Should the REST-specific function arguments be removed in the next minor release, or kept temporarily as deprecated no-op arguments?