Consider removing validation of transactions inside WASM

[dima74]

Do we need to validate transactions inside WASM? Potentially validation on the host should be enough and validation at WASM side could be removed as a small perofrmance optimization.

One option I can think of is to make SignedTransaction validation #[cfg(not(target_family = "wasm"))]

I like this suggestion. Can we say that since data model entities are always provided by the host there is no need to validate them on the wasm side? If so, we can can open a ticket to generalize this approach to all entities, although it seems kinda hacky and I'm not sure if this won't bite us in the ass

Originally posted by @mversic in #4793 (comment)