* Alerting: Add optional metadata to GET silence responses
- ruleMetadata: to request rule metadata.
- accesscontrol: to request access control metadata.
* Alerting: separate out silence auth service preconditions checks
Will be useful for subsequent PR that adds metadata to silence response
* Add silence read wildcard scope to precondition for read all silences
* Move alertmanager api silence code to separate files unchanged
* Replace with silence model instead interface
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Co-authored-by: Matt Jacobson <matthew.jacobson@grafana.com>
* extract genericService from RuleService just to reuse it later
* implement silence service
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Co-authored-by: William Wernert <william.wernert@grafana.com>
Co-authored-by: Matthew Jacobson <matthew.jacobson@grafana.com>