[extension/zpages] Add feature gate summary page

[Aneurysm9]

Signed-off-by: Anthony J Mirabella a9@aneurysm9.com

[codecov]

Codecov Report

Merging #4834 (f3b9edf) into main (ea897a6) will decrease coverage by 0.14%.
The diff coverage is 28.00%.

@@            Coverage Diff             @@
##             main    #4834      +/-   ##
==========================================
- Coverage   90.74%   90.60%   -0.15%     
==========================================
  Files         180      180              
  Lines       10593    10618      +25     
==========================================
+ Hits         9613     9620       +7     
- Misses        762      779      +17     
- Partials      218      219       +1     

Impacted Files	Coverage Δ
service/internal/zpages/templates.go	41.66% <25.00%> (-2.09%)	⬇️
service/zpages.go	70.33% <28.57%> (-9.05%)	⬇️

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[jpkrohling]

Should there be a link to http://localhost:55679/debug/featurez somewhere? It would also be good to have a mention of it in the readme.

[Aneurysm9]

Should there be a link to http://localhost:55679/debug/featurez somewhere? It would also be good to have a mention of it in the readme.

I added a link to servicez as it seems like the closest thing to a landing page.

[bogdandrutu]

Do you have a screenshot of the page?

[Aneurysm9]

It will look very empty right now as there aren't any feature gates defined in the core repo, but I added a few to demonstrate: