feat: upgrade Windows support to "feature"

[pendo324]

Issue #, if available:

Description of changes: Now that all infra/CI is setup and has been working stably for a few weeks, its time to mark Windows as a new "feature" so we can update Finch's next version number for the next release (tracked at #748).

Original Windows PR for reference: https://github.com/runfinch/finch/pull/649.

Testing done:

• [x] I've reviewed the guidance in CONTRIBUTING.md

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[pendo324]

Skipping CI since there is no diff