chore: Add alert/flash content replacement runtime API

[gethinwebster]

Description

Add runtime API for alert & flash content replacement

Related links, issue #, if available: ZnrFADMnL1Vy

How has this been tested?

New unit tests, updated screenshot pages

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.95%. Comparing base (2e32ba3) to head (538df4b).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2647      +/-   ##
==========================================
+ Coverage   95.94%   95.95%   +0.01%     
==========================================
  Files         746      748       +2     
  Lines       20676    20785     +109     
  Branches     7042     6697     -345     
==========================================
+ Hits        19837    19945     +108     
- Misses        831      832       +1     
  Partials        8        8              

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[pan-kot]

@just-boris, @gethinwebster, I rebased with main as there was a small conflicts with flashbar analytics changes. Please re-approve. Thanks!