Cosmos-sdk: CheckTx: Support ReCheck

[alexanderbez]

Tendermint's ABCI CheckTx now supports an enum Type field. The SDK should support and utilize this Type field, namely when the type is CheckTx_Recheck. In such a case, we should avoid (re)verifying the signature. Maybe there are other branches of logic we can avoid too.

/cc @AdityaSripal @ValarDragon

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[AdityaSripal]

From what I understand, skipping signature verification already gives us most of the efficiency gains.

But other branches I think we can avoid:

• Checking Sufficient Mempool fees
• tx.ValidateBasic

I believe Antehandler helper functions also need to be refactored. Since params might change in between 2 CheckTx's of the same tx, we should check that a tx still has enough gas to pay for signature verification without verifying the signatures themselves.

[alexanderbez]

Yeah, skipping ValidateBasic will offer some improvements, albeit small. But fee checking...what if the validator (somehow) changes their min fee between Commit and the next CheckTx for a given tx?

[AdityaSripal]

Is that possible without restarting the node?

[ValarDragon]

I think dynamic minimum fee changes based on market conditions should be anticipated. We don't see this because the chain has low tx volume.

[AdityaSripal]

I believe I can get this done as part of #5006

[alexanderbez]

Let's keep it as a separate PR @AdityaSripal for ease of review 👍