Fix visibility when creating a repository

[dbaur]

Description

Fixes #1456.

Calls toString method on the visibility enum in GHRepositoryBuilder ensuring the correct value in the request.

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[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.04% 🎉

Comparison is base (c283716) 80.04% compared to head (f4322fe) 80.08%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1692      +/-   ##
============================================
+ Coverage     80.04%   80.08%   +0.04%     
- Complexity     2231     2233       +2     
============================================
  Files           215      215              
  Lines          6760     6760              
  Branches        365      365              
============================================
+ Hits           5411     5414       +3     
+ Misses         1134     1132       -2     
+ Partials        215      214       -1     

Files Changed	Coverage Δ
...n/java/org/kohsuke/github/GHRepositoryBuilder.java	90.90% <100.00%> (+9.09%)	⬆️

... and 1 file with indirect coverage changes

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[dbaur]

One remark:

The issue also mentions that for some requests the repository is created with the wrong visibility. I think that this is due to GitHub API differentiating between the "visibility" field and the "private" field in its API.

When creating a repository for a user (i.e. not in an organization) and setting the visibility to "Visibility.PRIVATE" it seems that the API ignores the visibility setting if not also the _private method on the builder is set to true.

This can lead to confusing results, since one typically expects the visibility of the repository to be private when setting the visibility setting.

However, I am not sure if it is in the scope of this project to fix this problem of the GitHub API.