cli: improve error when attempting to invoke a non-existing contract

[tomerweller]

I accidentally tried to invoke a contract using the wasm hash as the id (yes, I'm an idiot). The cryptic response was:
error: Missing result in successful response. Can we put something more helpful?

Bonus points: Could we add a hint to the error in case the id looks like a wasm hash. "are you trying to use the wasm hash as a contract id"?

[fnando]

This doesn't seem to be the case anymore. Do you think we should do any additional work on this or is it clear enough?

$ stellar contract invoke --id 5ea0f3d6c880148c8da088809e851732127fc36b7b42bbdde6052fcc6f6253f3 --send=yes -- hello --to fnando
❌ error: contract not found: 5ea0f3d6c880148c8da088809e851732127fc36b7b42bbdde6052fcc6f6253f3

[leighmcculloch]

We could still test the input when no contract is found to see if it is a 32-byte hex string, and if so, change the error message to say "looks like this might be a wasm hash", the id should be a contract address.