Enable go-da to utilize multi accounts support from celestia-node

[tzdybal]

Imagine following use case:

• there is a shared celestia-node instance, providing DA for multiple rollups (operated by single org or even RasS provider, so they can setup keyring properly)
• each rollup need to use different key

Currently there is no way in go-da to specify key name. Possible solutions are:

• add key name as an option to Submit method (see: feat: add keyName #89)
• add generic ([]byte) param to Submit to enable passing any options
• add new method SubmiWithOptions with generic ([]byte) options
• add SetKeyName method to go-da interface
• add generic SetConfig([]byte) method to go-da interface
• leave go-da interface as is and extend proxy.GetClient to enable passing more options
  • actually the token is already similar use case (but seems way more generic than key name)

This is somehow similar to MaxBlobSize but the other way around. go-da interface is focused strictly on DA operation and not on life-cycle / metadata / configuration.

[tuxcanfly]

Another possible solution is to add a new method e.g. SubmitWithOptions(... Options []byte) which just forwards the options as a opaque bytestring to be decoded by the server.