Add navControlsPrimaryHeaderRight slot to header

[wanglam]

Description

This PR is for adding a new nav control slot for the primary header when the new home experience is enabled. There are many existing right nav control slots in the page header, but currently, there is no existing slot to add components to the right side of the primary header, next to the breadcrumbs bar.

Here are some screenshots to explain the existing slots in different page headers:

• Legacy page header (new home disabled):
  

• Application page header (new home enabled):
  

• Basic page header (new home enabled):
  

With this PR, a new nav control slot has been introduced to allow components to be placed in the primary header, next to the breadcrumbs bar, when the new home experience is enabled. Here's how it will look:

• Basic page header (new home enabled):
  

• Application page header (new home enabled):
  

Changelog

• feat: Add navControlsPrimaryHeaderRight slot to header

Check List

• All tests pass
  • yarn test:jest
  • yarn test:jest_integration
• New functionality includes testing.
• New functionality has been documented.
• Update CHANGELOG.md
• Commits are signed per the DCO using --signoff

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.67%. Comparing base (ca7c899) to head (6720a52).
Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   61.67%   61.67%           
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  Files        3817     3817           
  Lines       91719    91725    +6     
  Branches    14517    14517           
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+ Hits        56565    56569    +4     
- Misses      31524    31525    +1     
- Partials     3630     3631    +1     

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Linux_2	56.46% <100.00%> (+0.01%)	⬆️
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[ruanyl]

what does the "new primary chrome header" refer to?

[ruanyl]

So we're trying to introduce an API to register a global control button which is available for all application headers and page headers. Can we simply call it registerHeaderRight?

[wanglam]

I'm open to renaming it to registerHeaderRight. I just want to add some explanations for my naming convention. I added 'New' to distinguish it from the legacy header since this slot won't be displayed in that header. I added 'Primary' to distinguish it from the secondary header, as it's positioned on the right side of the primary header. Do you think this naming convention is reasonable? Using 'headerRight' is simpler, but I'm not sure if it might confuse others into thinking that the registered elements won't be displayed.

[ruanyl]

Thanks for the explanation! I got the point of "Primary" now :)
For "New", since legacy header is meant to be deprecated, so I don't feel necessary to distinguish it from the legacy one, imagine in the future, the legacy header was removed, then the "New" will sound a bit strange. what about calling it registerPrimaryHeaderRight?