feat(cli): allow multiple reverses

[PeculiarProgrammer]

Description

Issue #308 refers to the inability to reverse multiple times. I fixed this by decreasing the slide index by one if reverse was invoked twice consecutively with no next-slides in between.

More specifically, the issue mentions the following:

1. Reverse to the end of the previous slide
2. Go directly to the end of the previous slide
3. Go directly to the beginning of the previous slide

This PR fixes the first. The second option seems to be the same as the first just without the animation, so I don't think an implementation of that is needed. The third option seems to just be the back button without the animation, which I also don't think is necessary.

Fixes Issue

Closes #308

Check List

Check all the applicable boxes:

• I understand that my contributions needs to pass the checks;
• If I created new functions / methods, I documented them and add type hints;
• If I modified already existing code, I updated the documentation accordingly;
• The title of my pull request is a short description of the requested changes.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 80.96%. Comparing base (3dbe12b) to head (bd168f5).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
manim_slides/present/player.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #488      +/-   ##
==========================================
- Coverage   81.05%   80.96%   -0.09%     
==========================================
  Files          23       23              
  Lines        1884     1886       +2     
==========================================
  Hits         1527     1527              
- Misses        357      359       +2     

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[jeertmans]

Hi @PeculiarProgrammer, thanks for your contribution! I will review it when I have some free time, probably on Tuesday or later in the week, but that shouldn't take long! :-)

[jeertmans]

I have reviewed and it looks great, thanks! I will include a line in the changelog and merge.

[jeertmans]

Thank you for your contribution!