Deprecate legacy approval status names from `managed_licenses` API

RP

https://docs.google.com/document/d/1_PCNLq3csXN1S0jm5qsIkZjvgB7y_RIW-kuRF7Hmifo/edit

Proposal

We deprecated legacy names for approval status of license policy (blacklisted, approved) but they are still used in our API queries and responses. We need to fix it.

Implementation plan

1. In managed_licenses api file add new statuses denied and allowed to list of params and add mention in the description that blacklisted and approved are deprecated.
2. Update documentation and mention that “approved” or “blacklisted” are deprecated and are scheduled to be removed. New names are denied and allowed.

Testing

• Update relevant API unit tests https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/spec/requests/api/managed_licenses_spec.rb#L223
• Check that documentation https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/api/managed_licenses.md and https://docs.gitlab.com/ee/api/managed_licenses.html has been updated