Charge gas for contract KV store keys

[alpe]

Currently only the stored value is charged. With other cosmos modules the keys are build in Go and user input can not influence them very much but with our Wasm contracts the keys could be easily used for payload to bypass the gas metering. 🤪

[ethanfrey]

This is done in CosmWasm main, and I think will be back ported to 0.44.

Can we just rely on that and make a note about it somewhere (that people can back port PR x if they need it, otherwise available in next wasmd version)?

[ethanfrey]

This will be done in v2, when we upgrade to cosmos-sdk 0.44

[alpe]

Link for the sdk upgrade: #501

[ethanfrey]

This is in Cosmos SDK 0.45 and on master!