MudHighlighter: Fix Highlighted Markup Render Bug

[Anu6is]

Description

When Markup is enabled, if the highlight text is found within an html markup element, the markup rendering breaks and reverts to raw html. This fix excludes html tags from the highlighting process so as to avoid incorrectly inserting the <mark> tag into valid html elements.

Resolves: #10247
Resolves: #8196

How Has This Been Tested?

Visually and unit tests

Type of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (fix or improvement to the website or code docs)

Checklist

• The PR is submitted to the correct branch (dev).
• My code follows the code style of this project.
• I've added relevant tests.

[codecov]

Codecov Report

Attention: Patch coverage is 91.32653% with 17 lines in your changes missing coverage. Please review.

Project coverage is 91.18%. Comparing base (6027cf9) to head (b0ddd99).
Report is 1 commits behind head on dev.

Files with missing lines	Patch %	Lines
src/MudBlazor/Components/Highlighter/Splitter.cs	92.64%	5 Missing and 5 partials ⚠️
...Blazor/Components/Highlighter/MudHighlighter.razor	90.38%	2 Missing and 3 partials ⚠️
...zor/Components/Highlighter/MudHighlighter.razor.cs	75.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #11543      +/-   ##
==========================================
+ Coverage   91.17%   91.18%   +0.01%     
==========================================
  Files         466      466              
  Lines       14499    14652     +153     
  Branches     2815     2847      +32     
==========================================
+ Hits        13220    13361     +141     
- Misses        642      646       +4     
- Partials      637      645       +8     

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud