Navigate using mod rather than use

[ksnll]

When we visit, we now track both use statement and mod statements, and we use the latter to visit further files.
We also now keep track of ancestors, so we always know which module is importing any other module.

[codecov]

Codecov Report

Attention: Patch coverage is 97.25610% with 9 lines in your changes missing coverage. Please review.

Project coverage is 91.76%. Comparing base (c084648) to head (9c6215e).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/extricrate/src/lib.rs	97.25%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master       #2       +/-   ##
===========================================
+ Coverage    9.67%   91.76%   +82.08%     
===========================================
  Files           3        3               
  Lines          31      510      +479     
===========================================
+ Hits            3      468      +465     
- Misses         28       42       +14     

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[Copilot]

Pull Request Overview

This PR revises module navigation by tracking both use and mod statements and maintaining ancestor information for module imports.

• Introduces a new Visitor struct to record both use and mod declarations.
• Updates file traversal and test expectations to reflect the new module navigation strategy.
• Adds new structures and functions (e.g., FileToVisit and mod_to_path) to support the navigation logic.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
crates/extricrate/tests/fixtures/simple/src/module_a/module_b.rs	Adds a simple use statement for testing purposes.
crates/extricrate/tests/fixtures/simple/src/module_a/mod.rs	Registers module_b as a submodule via a mod declaration.
crates/extricrate/tests/fixtures/simple/src/main.rs	Declares module_a to initiate module navigation.
crates/extricrate/src/lib.rs	Updates the visitor logic and file traversal to incorporate mod statements and track module ancestors.