[DA_INDEXER] Celestia blobs indexer

[AllFi]

This PR introduces a simple indexer for Celestia blobs and a service to fetch blobs without the necessity to know a namespace beforehand. The Celestia indexer runs on top of the Celestia light node.

The name da-indexer was chosen because this service might potentially be extended to support other DA solutions (Avail, Eigen DA, etc.).

There are two potential use cases for this service:

1. This service might be useful for indexing Optimism-like rollups that use Celestia as a DA layer. The L1 transactions for this kind of rollup will include the height and commitment of the blob on Celestia. https://github.com/celestiaorg/optimism/blob/0ce4f69ef4fd113fae6f3ea0c99ea99a1dfc9c67/op-batcher/batcher/driver.go#L510
2. This service can also be used on UI to display the data of the batches in rollup settlement transactions on L1.

I've tested the indexer on the Celestia mainnet, and it seems to be working properly.

[rimrakhimov]

Imo, looks great

@AllFi Can we merge it?

[AllFi]

Hi, @rimrakhimov! Thank you for the review!

The current state of the indexer should be sufficient to cover the first Blockscout-Celenium use case, so I guess we can merge it.