Extend data handling for types larger than a WORD

[digorithm]

This is a follow-up to #112. Currently, we're checking for returned data size only for Strings and b256:

impl ParamType {
    // Checks whether the `ParamType` is bigger than a `WORD`
    pub fn bigger_than_word(&self) -> bool {
        match *self {
            Self::B256 => true,
            Self::String(size) => size > 8,
            _ => false,
            // More types will be handled later.
            // Currently, the support for arrays in the SDK is broken
            // due to a change to the array definition in Sway.
        }
    }
}

We need to extend this for the other types, more specifically custom types; Struct([u8]) should be smaller than a WORD, but Struct([u8, B256]) isn't.

[nfurfaro]

I think this is the last pain point for now on the SDK side of things for my work on the stdlib.
Any chance a fix might make it into the next release?
@digorithm

[digorithm]

Yeah that's the plan, next release should include it. I'm wrapping up something else and then I'll be working on this one, which shouldn't take too long!