Add Policy Author API spec

[janedotx]

See https://github.com/openmobilityfoundation/mobility-data-specification/issues/496

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[schnuerle]

See the notes from the last WG call.

• Way to update policies - create/add, draft, and deactivate policy
• Providers could get early access to review, heads up beforehand, part of conversation (not written that way now)
• Adds scope and access control levels to changes
• Maybe useful, as is doesn’t have connection between providers and agencies
• Where should this live, in its own MDS Admin new repo? WGSC conversation.
• Sherie Tan San Jose - wants it to be fair to vendors, could be helpful to have a testing area for providers.
• Explore it's use on the vendor side. Dirk says it could be useful to them