being able to query info and submit txs using the application alone and no rpc

[rach-id]

          I'm good with merging this now and handling some testApp tech debt later this week

if we do, let's just create issue for

• being able to query info and submit txs using the application alone and no rpc
• use the standard genesis code when building out testapp state

Originally posted by @evan-forbes in https://github.com/celestiaorg/celestia-app/pull/3942#pullrequestreview-2367433245