* added method for converting SamenessGroupConfigEntry
- added new method `ToQueryFailoverTargets` for converting a SamenessGroupConfigEntry's members to a list of QueryFailoverTargets
- renamed `ToFailoverTargets` ToServiceResolverFailoverTargets to distinguish it from `ToQueryFailoverTargets`
* Added SamenessGroup to PreparedQuery
- exposed Service.Partition to API when defining a prepared query
- added a method for determining if a QueryFailoverOptions is empty
- This will be useful for validation
- added unit tests
* added method for retrieving a SamenessGroup to state store
* added logic for using PQ with SamenessGroup
- added branching path for SamenessGroup handling in execute. It will be handled separate from the normal PQ case
- added a new interface so that the `GetSamenessGroupFailoverTargets` can be properly tested
- separated the execute logic into a `targetSelector` function so that it can be used for both failover and sameness group PQs
- split OSS only methods into new PQ OSS files
- added validation that `samenessGroup` is an enterprise only feature
* added documentation for PQ SamenessGroup
This commit adds a sameness-group config entry to the API and structs packages. It includes some validation logic and a new memdb index that tracks the default sameness-group for each partition. Sameness groups will simplify the effort of managing failovers / intentions / exports for peers and partitions.
Note that this change purely to introduce the configuration entry and does not include the full functionality of sameness-groups.
