Add CreateOrUpdateCustomPropertyValues for repositories

[HariCharanK]

Fixes:
#3101

Followup PR to #3104

Used interface{} type for PropertyValue as it can be string, array or null according to the GitHub documentation here.

In Go, an interface{} can hold any type, including an array (or slice) of strings.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.88%. Comparing base (2b8c7fa) to head (e581a20).
Report is 43 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3105      +/-   ##
==========================================
- Coverage   97.72%   92.88%   -4.84%     
==========================================
  Files         153      170      +17     
  Lines       13390    11426    -1964     
==========================================
- Hits        13085    10613    -2472     
- Misses        215      723     +508     
  Partials       90       90              

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[gmlewis]

If you could revert all the changes that are already covered by #3104, that would be great.
Otherwise, we will wait on reviewing this PR until #3104 is merged.

Just a heads-up... we try to avoid using interface{} as much as possible in this repo, but in some places we simply can't avoid it.
I don't have time now to review this PR but will hopefully have time this weekend.

[HariCharanK]

The changes in this depend on changes in #3104, so we should wait until it's merged. I don't see otherwise.

" we try to avoid using interface{} "
I see, I'll update if I can do something else instead.

[HariCharanK]

resolved merge conflicts.

[gmlewis]

@HariCharan-001 - as far as I can tell, this PR is not addressing the issue in #3101 which is to add a PATCH endpoint for this: https://docs.github.com/en/rest/repos/custom-properties?apiVersion=2022-11-28#create-or-update-custom-property-values-for-a-repository

[HariCharanK]

@gmlewis
are there any generic issues caused by using interface{} other than lack of type safety and minute impact on performance ?

Do you think it is necessary to avoid using interface{} in this particular scenario ?
I could think of a couple ways, but they may affect code readability and simplicity. What's the trade-off here ?

[gmlewis]

The interface {} issue, I think, is secondary to the issue above.