Create demo Bitcoin transaction verification

[webmaster128]

This replaces #754. We now have crypto API's secp256k1_recover_pubkey and secp256k1_verify. This should be the only building blocks needed by the contract to verify Bitcoin thransaction. The rest is encoding and hashing, which is done in the contract.

In this ticket, we want a comple example of a Bitcoin transaction verification in the development contract https://github.com/CosmWasm/cosmwasm/tree/main/contracts/crypto-verify

Interesting material:

• Bitcoin address derivation from secp256k1 pubkeys: https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses

[webmaster128]

This is done in a different repo and can be ported over easily. Turns out that a Bitcoin signature verification does not mean you can unlock an input. So the value for a Bitcoin application is questionable. However it shows one part. Also it brings in DER signature decoding, which Ethereum did not need at the end of the day.

[webmaster128]

Out of scope for now