fix(insights): Cache page alert re-rendering

[narsaynorath]

We should only be triggering the set state for the alert to undefined if we're not already undefined, i.e. prevents an infinite loop of renders.

The page alert context provides setters that were getting re-created each time the state changed. Wrap the setters in useCallback so the reference to the functions are always the same. This way, hooks that list these functions as dependencies don't go rampant.

[codecov]

Bundle Report

Changes will increase total bundle size by 330 bytes ⬆️

Bundle name	Size	Change
app-webpack-bundle-array-push	28.18MB	330 bytes ⬆️

[DominikB2014]

@narsaynorath shouldnt setting state to the same value yield no rerenders?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.14%. Comparing base (26e6464) to head (0ac8262).
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #74737   +/-   ##
=======================================
  Coverage   78.14%   78.14%           
=======================================
  Files        6730     6730           
  Lines      300110   300110           
  Branches    51623    51623           
=======================================
  Hits       234529   234529           
- Misses      59256    59259    +3     
+ Partials     6325     6322    -3     

Files	Coverage Δ
...tatic/app/utils/performance/contexts/pageAlert.tsx	62.85% <100.00%> (ø)

... and 1 file with indirect coverage changes

[narsaynorath]

@DominikB2014 I agree and thought it was weird so I dug a bit deeper and it looks like it's because of referential inequality. Basically when we trigger the setPageInfo function, it creates a new setPageInfo callback. I think we could potentially fix this by wrapping the settings with useCallback