[ADD] ante handler plumbing
Adds a copy of the cosmos ante handler and customizes it with a new thorchain ante decorator. This decorator currently does the same logic as !2762 (merged) but rejects such messages earlier, not even allowing them into the mempool.
It also has dummy functions for each message handler which can/will be filled in with more checks to further tighten up the chain, early-outing at the mempool when appropriate.
Each of the dummy funcs has the same comment about the behavior of the ante function. Open to suggestions on making that comment clearer, etc.
STAGENET TESTING
- same as !2762 (merged) but instead of committing the failed tx to the chain with an error, the tx should be rejected from the mempool and not allowed on chain
Edited by akrokr