[dvc] dvc node blob discovery

[ishwarya-citro]

Summary, imperative, start upper case, don't end with a period

Implemented a new API endpoint designed to facilitate the bootstrapping of nodes by identifying and listing live nodes prepared to serve the store's blobs. If the blob transfer feature is enabled for the store, it retrieves each node's hostname from the push store, given that these nodes are alive.

How was this PR tested?

integ. test cases

Does this PR introduce any user-facing changes?

• [x] No. You can skip the rest of this section.
• [ ] Yes. Make sure to explain your proposed changes and call out the behavior change.