Temporary default stateMutability to payable in ABI

[cburgdorf]

What was wrong?

The ABI metadata that we generate does currently not include the stateMutability field. This piece of information is important for tooling such as hardhat because it determines whether a function needs to be called with or without sending a transaction.

As soon as we have support for mut self and mut ctx we will be able to derive that information from the function signature. In the meantime we should default to payable.

How was it fixed?

Add stateMutability field and default it to payable.

[Jzow]

Do you mean to add a parameter to the &mut variability of rust to control the variability of the function?

[cburgdorf]

@Jzow Take a look at the "abi conformity" section of #558
In the future we will have support for the mut keyword enabling us to take self or mut self and ctx or mut ctx. We can then derive the stateMutability section of the ABI based on that. For now, we can not which gives tooling such as hardhat a hard time because it can not infer whether a function needs to be called with a transaction or if a readonly call would do it.