Add route and view for Compare rapid diffs view

What does this MR do and why?

Add route and view for Compare rapid diffs view

Adds a new route and view for rapid diffs on the compare page. Makes it only accessible behind the rapid_diffs ff and with the rapid_diffs query param being set to true

MR acceptance checklist

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	with ?rapid_diffs=true	withOUT ?rapid_diffs=true
When there is diff
When there is no diff
When feature flag is off

How to set up and validate locally

• Enable rapid_diffs feature flag
• Visit /NAMESPACE/PROJECT/-/compare/BRANCH1...BRANCH2?rapid_diffs=true
  • For example, http://gdk.test:3000/flightjs/Flight/-/compare/master...trigger-hook?rapid_diffs=true

Related to #451780