Add dependent module information in meta information.

[jonasthewolf]

• [x] Add documentation on feature
• [x] Describe that main file should be called index.gsn.yaml
• [x] Add tests
• [x] Verify that character wrap handling in program is consistent now
• [x] Prevent endless loop if user creates circular dependencies
• [x] Remove relative path restriction
• [x] If no relative path can be found (e.g. different drives on Windows) keep absolute links
• [x] TODOs in comments added for this Decide how the module.name should be built if not given
• [x] Rename attribute to "uses"
• [x] Search for "index.gsn.y[a]ml" by default. If not found and no input files are named, show help.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 95.12195% with 38 lines in your changes are missing coverage. Please review.

Project coverage is 98.52%. Comparing base (94b08a3) to head (612eb50).

Files	Patch %	Lines
src/main.rs	87.40%	34 Missing :warning:
src/file_utils.rs	98.31%	2 Missing :warning:
src/gsn/mod.rs	96.66%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #415 +/- ## ========================================== - Coverage 98.66% 98.52% -0.14% ========================================== Files 22 22 Lines 5375 5620 +245 ========================================== + Hits 5303 5537 +234 - Misses 72 83 +11 ```

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