fix(RouteTreeView): Misc UX improvements

[surajshetty3416]

• Load all pages in the frontend and load in the frontend with some threshold. More pages are loaded on demand by clicking load more
• Add arrow key shortcuts to navigate the tree
• Add unpublish option to the page action dropdown
• Fix node alignment and styling

Before:

After:

continuation of: #589

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.62%. Comparing base (e27292c) to head (c5bcc27).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #591   +/-   ##
========================================
  Coverage    57.62%   57.62%           
========================================
  Files           29       29           
  Lines         3193     3193           
========================================
  Hits          1840     1840           
  Misses        1353     1353           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.