feat: use shared test files and update snapshots

[nyurik]

This PR includes #16 - make sure to merge it first

• Note that long_names.dbc has been modified upstream, so I copied the original to the mytest dir.
• In the next PR, I will remove the dbc/dbc-cantools

[Copilot]

Pull Request Overview

This PR introduces shared test files infrastructure and updates snapshots for DBC parsing tests. The primary purpose is to consolidate test resources by using a shared test files submodule while maintaining backwards compatibility with existing local test files.

Key changes:

• Implement a snapshot-based testing framework using the insta crate
• Add support for testing DBC files from both shared and local directories
• Generate comprehensive YAML snapshots for parsed DBC structures

Reviewed Changes

Copilot reviewed 89 out of 167 changed files in this pull request and generated 1 comment.

File	Description
tests/snapshots.rs	New test infrastructure that parses DBC files and generates snapshots from multiple directories
tests/snapshots-mytest/*.snap	YAML snapshots for local test DBC files in the mytest directory
tests/snapshots-dbc-cantools/*.snap	YAML snapshots for shared cantools DBC test files

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[nyurik]

@MDGSF thank you for reviewing! It's ok not to merge my PRs because I have the rights to do it. It is better to let me do it - because I may spot additional issues right before merging.