feat(context): add repository path to template context

Description

You can now use {{ repository }} variable in the template to get the repository path.

This is especially useful when you use git-cliff with multiple repositories. (e.g. git-cliff -r repo1 -r repo2)

Motivation and Context

see #685

How Has This Been Tested?

Unit tests.

Types of Changes

[ ] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] Documentation (no code change)
[ ] Refactor (refactoring production code)
[ ] Other

Checklist:

[x] My code follows the code style of this project.
[x] I have updated the documentation accordingly.
[x] I have formatted the code with rustfmt.
[x] I checked the lints with clippy.
[x] I have added tests to cover my changes.
[x] All new and existing tests passed.

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 36.65%. Comparing base (3eb828e) to head (6cdf69c).

Files	Patch %	Lines
git-cliff/src/lib.rs	0.00%	2 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #721 +/- ## ========================================== - Coverage 36.72% 36.65% -0.07% ========================================== Files 19 19 Lines 1498 1501 +3 ========================================== Hits 550 550 - Misses 948 951 +3 ``` | [Flag](https://app.codecov.io/gh/orhun/git-cliff/pull/721/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Orhun+Parmaks%C4%B1z) | Coverage Δ | | |---|---|---| | [unit-tests](https://app.codecov.io/gh/orhun/git-cliff/pull/721/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Orhun+Parmaks%C4%B1z) | `36.65% <50.00%> (-0.07%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Orhun+Parmaks%C4%B1z#carryforward-flags-in-the-pull-request-comment) to find out more.

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orhun / git-cliff