Abigen finds std::string::String over sway-lib's String

[bitzoic]

When attempting to pass or return the sway-libs String type, abigen mistakes this for Rust's standard library string.

For example, running a test on the following Sway code generates this error:

contract;

use sway_libs::string::String;

abi MyContract {
    fn test_get() -> String;
    fn test_set(new_string: String);
}

impl MyContract for Contract {
    fn test_get() -> String {
        String::new()
    }

    fn test_set(new_string: String) {
        
    }
}

The Sway-lib's String is currently simply a wrapper on Sway's Vec:

pub struct String {
    bytes: Vec<u8>,
}

[segfault-magnet]

@bitzoic there is a problem with the name collision, so I'll fix that in this task.

But note that you can't return anything containing a vector until this task is done.

Even then I fear you won't be able to return this as there was an inter-team meeting on which we agreed that returning vectors will be supported only at the topmost level -- i.e. fn something() -> Vec<Something>

Even though the nesting of the vec inside Sway's string is superficial (i.e. it will be encoded exactly as a top-level-vec would be), this still might be prohibited by the compiler once the 'vec-as-output' support is done on the Sway side.

@mohammadfawaz fyi.