fix(common): properly parse functions in their usual form

[Evalir]

Closes #6135

Alloy's Function only parses functions without their return arguments and without the function prefix. We can use AbiItem::parse to parse them as human-readable abi strings and get a Function in return.

[mattsse]

let's add a few sanity tests here

[Evalir]

Added a test @mattsse — albeit we'll need a new feature in alloy to parse full function signatures. Right now we can only parse either stripped functions or human-readable ABI functions which don't support visibility modifiers. cc @DaniPopes

ref alloy-rs/core#389