Support tests that depend on modules

[lawrence-laz]

The adapter can now run single test files, but if they have dependencies on other modules, the tests will never pass. An example can be found in nested container tests from zig docs.

Ideally the user should not have to do anything else, and the tests should import required modules.

[lawrence-laz]

Update on this: a rewrite is in progress, basic scenario now works with both zig test for individual files and zig build test for projects with modules and build.zig.

There are still quite a few edge cases to handle, but it's going good.

[lawrence-laz]

Initial implementation was done here: https://github.com/lawrence-laz/neotest-zig/commit/ba4db6d96763f9243e060f18cff8149f58c76824

[lawrence-laz]

Resolved by 288a25667f15e3c86937adf66c1f1d8f7c05324b