[frontend] Detect changes in CK Editor when in Source mode (#8694)

[Archidoit]

Proposed changes

In the Content tab of a Container, in the text area to edit an html file, detect changes when in Source mode to be able to save the changes in Source mode.

Related issues

#8694

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.53%. Comparing base (e8172c0) to head (87a166d).
Report is 42 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10656      +/-   ##
==========================================
- Coverage   65.54%   65.53%   -0.01%     
==========================================
  Files         672      672              
  Lines       66971    66971              
  Branches     7357     7353       -4     
==========================================
- Hits        43894    43889       -5     
- Misses      23077    23082       +5     

☔ 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.

[SarahBocognano]

The saving works correctly. The UX is not incredible to see that the text is actually saved, but it's not the subject of the bug here