* refactor: migrator and introduce Store.(Create|Delete)Bucket
feat: kvmigration internal utility to create / managing kv store migrations
fix: ensure migrations applied in all test cases
* chore: update kv and migration documentation
* feat(kv): migration types for managing kv buckets and indexes over time
chore(kv): fixup comments in migrator types
fix(kv): initialize migrator bucket on kv service initialize
chore(kv): remove currently unused auth index
chore(kv): remove currently unused urm index
* chore(kv): move migrator tests into testing package and run for inmem and bolt
* chore(changelog): update changelog to reflect kv migrator type
* fix(kv): update auto migration store to return migratable store
* chore(kv): wrap error using func instead of defer in index
* chore(kv): rename Name method to MigrationName for clarity
* chore(kv): update migration log messages to match influxdb standard
George
Jonathan A. Sternberg