This renames `data` to `expressions` for clarity in the rules apis.
Also makes certain fields that are redundant optional in the case of pure expressions, so that users don't have to specify them when they are not needed (e.g. not datasource queries).
Rules created in the new api makes the rule have no group in the database, but the rule is returned in the old group api with a sentinel group name formatted with the rule uid for compatiblity with the old api.
This makes the UI continue to work with the rules without a group, and the ruler will continue to work with the rules without a group.
Rules are not allowed to be created in the provisioning api with a NoGroup sentinel mask, but NoGroup rules can be manipulated through both the new and old apis.
Co-authored-by: William Wernert <william.wernert@grafana.com>
The first version of the app platform apis for alerting rules, including AlertRule and RecordingRule definitions.
Co-authored-by: William Wernert <william.wernert@grafana.com>
