TPv2 Add page title setting when header title is updated

[ocket8888]

Closes #2742

This PR updates navigation in the experimental TPv2 to also update the page title in the browser whenever the page's header title is set.

---

Which Traffic Control components are affected by this PR?

• Traffic Portal (experimental v2)

What is the best way to verify this PR?

Make sure the tests pass. To verify manually, go to a bunch of pages and ensure the web page's title always matches the page header's title.

PR submission checklist

• This PR has tests
• This PR doesn't need documentation
• This PR doesn't need a CHANGELOG.md entry
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (adea91d) 28.84% compared to head (4fd7507) 65.65%.
Report is 3 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##             master    #7915       +/-   ##
=============================================
+ Coverage     28.84%   65.65%   +36.80%     
  Complexity       98       98               
=============================================
  Files           602      323      -279     
  Lines         77445    12840    -64605     
  Branches         90      970      +880     
=============================================
- Hits          22342     8430    -13912     
+ Misses        53012     4050    -48962     
+ Partials       2091      360     -1731     

Flag	Coverage Δ
golib_unit	?
grove_unit	?
t3c_unit	?
traffic_monitor_unit	?
traffic_ops_unit	?
traffic_portal_v2	74.37% <100.00%> (?)
traffic_stats_unit	?
unit_tests	74.37% <100.00%> (+48.70%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

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