Clean up validation logic

[cmwaters]

Summary

The way we validate the block and the transactions contained within that block is currently quite messy and spread out across the repo. This makes it difficult to follow what the actual validity rules are.

This arises predominantly because we have an introduced type BlobTxs which while a transaction, doesn't fit into the AnteHandler system. Thus BlobTx validation logic lives outside antehandlers. This means that logic such as restricting the total tx size also lives outside the antehandlers.

Proposal

There are various approaches:

• modify the antehandler function signature: we could add an array of blobs to that field which would allow us to perform all transaction validation within antehandlers. However this would be an intrusive change to the existing cosmos sdk - we could circumvent this by just having a wrapper which would make it backwards compatible (a similar wrapper exists already for version gating the antehandlers)
• create a blobTx antehandler: which is run just for blobTxs while the antehandler is run for non PFB transactions.