MudNavGroup: Add TitleContent parameter

[Ben0421]

Description

A TitleContent render fragment was added in the component MudNavGroup. There was a way to add custom content to all the other Nav Menu's components except this one. The implementation is very similar to MudExpansionPanel's TitleContent where TitleContent takes precedence over Title.

How Has This Been Tested?

No test were added. An example has been added in the docs. It has only been tested visually since the change doesn't include any logic.

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)

Here the example added in the docs for this new feature:

LTR

RTL:

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

All modified and coverable lines are covered by tests ✅

Project coverage is 91.22%. Comparing base (44f0b71) to head (23f5440).
Report is 6 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev   #10160   +/-   ##
=======================================
  Coverage   91.22%   91.22%           
=======================================
  Files         411      411           
  Lines       12484    12485    +1     
  Branches     2434     2435    +1     
=======================================
+ Hits        11389    11390    +1     
  Misses        552      552           
  Partials      543      543           

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[danielchalmers]

You could make the argument it should have a different class but I think it's fine

[henon]

Thanks @Ben0421