feat: Add feature to reset markdig extension settings that are added by default

[filzrev]

This PR intended to add functionality to use Markdig extensions with default settings.

Background
There are some PRs(#9762/#9772) are created that request changing markdig extensions setting to support advanced syntax.
But these change might break existing markdown documents.

So these changes are should be enabled as opt-in features.

What changed in this PR
This PR add functionality to reset settings when existing known markdown extension names are specified.
(And it preserve extension orders.)

Usage
When specify existing "markdigExtensions" names.
These markdig extensions are replaced with markdig default settings.

{
  "build": {
    "markdownEngineProperties": {
      "markdigExtensions": [
        "EmphasisExtras",
        "Emojis"
      ]
    }
  }
}

[codecov]

Codecov Report

Attention: Patch coverage is 77.77778% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 79.02%. Comparing base (fe673ec) to head (46268af).
Report is 93 commits behind head on main.

❗ Current head 46268af differs from pull request most recent head a6c4c83. Consider uploading reports for the commit a6c4c83 to get more accurate results

Files	Patch %	Lines
...cfx.MarkdigEngine.Extensions/MarkdownExtensions.cs	77.77%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9780      +/-   ##
==========================================
+ Coverage   74.31%   79.02%   +4.70%     
==========================================
  Files         536      536              
  Lines       23189    23193       +4     
  Branches     4056     4028      -28     
==========================================
+ Hits        17234    18328    +1094     
+ Misses       4853     3746    -1107     
- Partials     1102     1119      +17     

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[yufeih]

These feel like configuration of existing extensions, it might be more future proof if we configure it such as:

markdigExtensions: [
    'other-extensions'
    { emoji: { enableSmileys: true }],
    { autoidentifier: 'default' }
]

[filzrev]

I've added commented features to override extension properties by PR #9820.

Example configs

markdigExtensions: [
    "FootNotes",
    { "Emojis": { "options": {  "enableSmileys": true } },
    { "AutoIdentifiers": { "options": 'default '} },
    { "MediaLinks": { "options": { "width": 800, "height": 400 }} 
]

Note: I've added options key. Because it might required to support additional property
when implementing remove markdig extensions that are enabled by default feature.(Discussed at #7833)

[filzrev]

Close this PR.

When resolving PR conflicts. Unintended file changes are pushed.
To clearer change histories.
I've created another PR (#9820).