Reimplement `da/celestia` using `rollkit/celestia-openrpc`

[tzdybal]

### Tasks
- [ ] https://github.com/rollkit/rollkit/issues/995
- [x] Add OpenRPC client instance to da/celestia
- [ ] https://github.com/rollkit/rollkit/issues/980
- [x] Reimplement `SubmitBlock` method
- [x] Reimplement `CheckBlockAvailability` method
- [ ] Reimplement `RetrieveBlocks` method
- [x] Remove go-cnc dependency

[tzdybal]

Proposition of work plan:

1. Start by adding dependency and token and openrpc client instance to da/celestia
2. Implement each method separately (can be parallelized!)
3. Remove go-cnc dependency

By removing go-cnc at the end, and keeping "mixed" implementation, we can actually work on methods separately, without breaking the tests.

[tuxcanfly]

Working on adding mock handlers for the new endpoints.