feat: Add support for Oracle OCI object storage

[smuth4]

With the addition of the objstore library, this becomes a pretty simple addition. I used the exact same config struct as objstore, but only added the most relevant ones to the command line flags to avoid cluttering things up. This has been running successfully for a couple days in a small kubernetes cluster with loki-canary.

I wasn't sure where the best place in the docs would be to add an example config since (AFAICT) this is the first storage client that is only supported via objstore, but if I get some direction I'd be happy to do a little write-up:

storage_config:
  use_thanos_objstore: true
common:
  storage:
    object_store:
      oci:
        provider: oke-workload-identity
        bucket: <bucket name>
        region: <region name>

What this PR does / why we need it:
While OCI does have a S3 compatibility layer that can be used to get loki working as per #7713 (comment), supporting it natively allows for a much simpler setup (e.g. workload identity in kubernetes). While I have not done any load/stress testing, one would also hope the native APIs will be faster.

Which issue(s) this PR fixes:
Fixes #7713

Special notes for your reviewer:
Given how small the actual integration is I didn't see any place to write a useful test, but I'd be willing to put in the work there if needed.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• [N/A] Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR