- BifrostAdmin can now init empty logs configuration
- BifrostAdmin can now auto extend the chain
- Providers now have control over suggesting a new segment configuration
- Introduces a temporary copy of NodeSetSelector into bifrost until log-controller is removed

…etadataWriter

This PR introduces two key changes:

1. Bifrost now can provide `bifrost.admin()` to get easy access to bifrost's admin interface withouto passing metadata writer and metadata store client explicitly.
2. MetadataWriter now owns MetadataStoreClient.


This means that you can always access metadata store client directly if you have metadata_writer which used to be a pair of types we _always_ pass together. This also opens a path for a future where MetadataWriter wraps the metadata store client and automatically update metadata manager on successful writes but that's beyond the scope of this PR. What this PR provides is a direct access to the underlying metadata_store_client via an accessor function.

BifrostService will not auto provision its own metadata entry in metadata store on startup.