Fix cursor showing and hiding

[ianthomas23]

The cursor showing and hiding logic that I previously implemented via the cursor_hider scope object was buggy in that it could end up leaving the cursor hidden at the end of a git2cpp command. This would happen, for example, using a prompt_input which ensures that the cursor is enabled when the prompt is shown and then hides it at the end. The solution, in the presence of potentially nested cursor_hider objects, is to keep a static count of the number of active scope objects and ensure the cursor is shown when this goes down to zero.

It does introduce a static variable which isn't ideal but it is only a single unsigned int.

This is very hard to test, so I am not doing so in CI but I have tested it manually in both macos and wasm builds.

[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 87.23%. Comparing base (ad032f0) to head (26347d1).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/utils/input_output.cpp	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #141      +/-   ##
==========================================
- Coverage   88.27%   87.23%   -1.04%     
==========================================
  Files          61       61              
  Lines        2627     2633       +6     
  Branches      309      310       +1     
==========================================
- Hits         2319     2297      -22     
- Misses        308      336      +28     

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[ianthomas23]

Fixes #129.