Fix codeblock parsing

[artcodespace]

Fixes #493 (the codeblock part).

Integrating this into element web (PR still to be opened) will fix the list issue in the linked issue above.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.26 ⚠️

Comparison is base (244d6db) 90.20% compared to head (222faca) 89.95%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #738      +/-   ##
==========================================
- Coverage   90.20%   89.95%   -0.26%     
==========================================
  Files         113       83      -30     
  Lines       16034    14598    -1436     
  Branches      565        0     -565     
==========================================
- Hits        14464    13131    -1333     
+ Misses       1550     1467      -83     
+ Partials       20        0      -20     

Flag	Coverage Δ
uitests	?
uitests-ios	?
unittests	89.95% <100.00%> (+0.98%)	⬆️
unittests-ios	?
unittests-rust	89.95% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
...yg/src/dom/parser/markdown/markdown_html_parser.rs	100.00% <100.00%> (ø)

... and 30 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[aringenbach]

LGTM