preprocessor to skip recompiling tests on non-interface source file changes

[grandizzy]

supersedes #198

• rebased with main
• uses solar instead solang to compute interface representation

Implements preprocessor allowing us to skip recompiling tests on non-interface source file changes. Still testing, but looks like it's working correctly, decreasing single-change build times from ~1 minute to 5s in some cases.

TODOs

• opt-in caching changes
• use solar HIR
• additional testing

[DaniPopes]

please import ast instead of using crate name::

[grandizzy]

yep, done, will clean more imports when moving to use solar HIR 594c09b

[DaniPopes]

this should use solar HIR, requires patching to latest git

[grandizzy]

@DaniPopes I am having some difficulties figuring out how to use HIR API (trying smth like below), could you please shed some light? thank you!

        sess.enter_parallel(|| -> solar_parse::interface::Result {
            let sources = sources.into_iter().map(|(path, _)| path);
            let mut parsing_context = ParsingContext::new(&sess);
            parsing_context.load_files(sources)?;
            parsing_context.parse_and_resolve()?;
            /// Do something with parsed sources, access HIR
            Ok(())
        });