* 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
this is a step towards providing a shared http client that manages pooling connections,
timeouts, and reducing GC for by not creating/GCing a client each req. Bring on the red!
* feat(kv): unique variable names
- adds system bucket for creating an index of unique variable names
- adds tests
- deleted unit tests for dead code
- removed a test runner for the variable service from http