Spec Lite: Deprecate Images API v1 Support

problem: The Images API v1 is targeted to be removed in Rocky, hence there is no reason to continue carrying v1 support in the glanceclient.
solution: Announce that the Rocky release of the python-glanceclient will be the last release that will support the Images v1 API and that support will be removed in the first major release of the S cycle.
impacts: DocImpact
alternatives: Continue to support the Images API version 1. This is not necessary for interoperability, however, as the Images API v1 was never included in "DefCore" tests. Continued support would not be a good use of the team's time.
timeline: Early Rocky cycle
link: https://blueprints.launchpad.net/python-glanceclient/+spec/deprecate-v1-support
reviewers: all core reviewers
assignee: jokke