[Feature Request]: Multiple celestia accounts can submit blobs via 1 DA Node

[Bidon15]

Implementation ideas

In order to save costs, users want to host many execution environments on top of 1 DA Node (can be a bridge node)
To achieve this, node should have the notion of submitting blobs on behalf of many celestia accounts

Ref:

1. Support multiple keys within signer celestia-app#3259
2. [Feature Request]: Signer util for node wallet api celestia-app#3246

Part of #3022

[renaynay]

state.SubmitPayForBlobWithOptions takes a state.PayForBlobOptions struct which has a field KeyName that specifies the name of the key that the CoreAccessor should use when submitting that specific blob.

The signer can be constructed dynamically once the key by the given name is successfully loaded from the keystore as a work-around for the signer not being able to support multiple keys in the meantime.

state.SubmitPayForBlobWithOptions should be exposed via BlobModule as blob.SubmitWithOptions and should propagate the request down to the node in a similar way to blob.Submit.

[renaynay]

Finished as a part of v0.15.0 :)