[Feat.Req] Add indexer management server url

[hopeyen]

Problem statement

Currently the radio only connects to the Graph node, but doesn't connect to the indexer components. For any management of indexing status, the radio should go through indexer's server for consistency in management.

Expectation proposal

• Add indexer_management_server_url: Option<String> to radio configs.
• Add auto_upgrade: Coverage (default: comprehensive) to radio configs.
  • Add none as a variant to the Coverage enum
• Add validation to the url upon startup if url is provided.

Related to #6