Investigate, remove and disallow the usage of the floats in WASM

[tzemanovic]

follow-up to #3275

We need to investigate, remove and disallow usage of the floats. I had a look and some usage comes from tendermint-rs and its use serde_json which should be easy to replace by serde_json_wasm. Other use in wasm tx_ibc seems to be pulled in from schemars (transitive dep of ibc) and ethbridge-structs, but those may not be an issue.

While at it, we should also replace our usage of serde_json by serde_json_wasm

[tzemanovic]

I found one of the sources of floats in tx_ibc wasm is ClientState protobuf decoding, but I tried to temp remove that code and there seem to be more than that