fix!: Fix field selection and bugs in ProjectsV2 GET endpoints

[stephenotalora]

BREAKING CHANGE: UpdateProjectItemOptions.Field is now []*ProjectV2FieldUpdate.

Discovered these issues while integrating the related project item APIs exposed in V77.

Fixes bugs in the implementation of support for field selection and updates in the following project item endpoints:

• Properly handles URL parameters for field selection in GetOrganizationProjectItem and GetUserProjectItem.
• Corrects field update struct and request payload formatting in UpdateOrganizationProjectItem and UpdateUserProjectItem.

Adds or updates tests to verify correct handling of these cases.

Covers:
https://docs.github.com/en/rest/projects/items?apiVersion=2022-11-28

Related REST API docs:

• https://docs.github.com/en/rest/projects/items#get-a-project-item
• https://docs.github.com/en/rest/projects/items#update-project-item-for-organization
• https://docs.github.com/en/rest/projects/items#get-a-project-item-for-a-user
• https://docs.github.com/en/rest/projects/items#update-project-item-for-a-user

Complements: #3793

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.28%. Comparing base (1b0a91c) to head (98c0d60).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3809   +/-   ##
=======================================
  Coverage   92.27%   92.28%           
=======================================
  Files         192      192           
  Lines       13896    13902    +6     
=======================================
+ Hits        12823    12829    +6     
  Misses        884      884           
  Partials      189      189           

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[gmlewis]

Thank you, @stephenotalora!
Please add testBadOptions to all your new unit tests to improve the code coverage.

[stephenotalora]

Thank you, @stephenotalora! Please add testBadOptions to all your new unit tests to improve the code coverage.

Good catch, @gmlewis 🙇🏼 fixed! I was deep in the bug fixes and glossed over that. 👍

[gmlewis]

Thank you, @stephenotalora!
LGTM.
Awaiting second LGTM+Approval from any other contributor to this repo before merging.

cc: @stevehipwell - @alexandear - @zyfy29

[alexandear]

Why not?

Suggested change

	type ProjectV2FieldUpdate struct {
	type UpdateProjectV2Field struct {