fix: update demo with lastest tiny updates

[xjiang-at-wiris]

Description

Update the demo and documentation to include the workaround for using extended_mathml_elements, extended_mathml_attributes.

These changes are made to ensure that MathML generated by MathType works correctly during both editing and viewing in TinyMCE 7, following it's 7.8 release note.

• Related Kanbanize Card: Link to KB-55936

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Documentation update (changes to documentation only)

Checklist

• My code follows the style guidelines of this project ( Run yarn lint to check)
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• New and existing unit tests pass locally with my changes

How should be tested? (Manual or Automated Tests)

1. Launch tinycme 7' demo.
2. Try to add formulas with linebreak. For example:
   <math style="font-family:'Times New Roman'" xmlns="http://www.w3.org/1998/Math/MathML"><mi>A</mi><mi>B</mi><mo>=</mo><mi>A</mi><mi>C</mi><mo>,</mo><mspace linebreak="newline"/><mspace/><mspace/><mspace/><mspace/><mspace/><mspace/><mspace/><mspace/><mi>A</mi><mi>K</mi><mo>=</mo><mi>A</mi><mi>H</mi><mo>,</mo><mspace linebreak="newline"/><mspace/><mspace/><mspace/><mspace/><mspace/><mspace/><mspace/><mspace/><mi>B</mi><mi>K</mi><mo>=</mo><mi>C</mi><mi>H</mi><mo>&#xA0;</mo><mo>?</mo><mi mathvariant="normal">&#x3C0;</mi></math>
3. Ensure the MathML is not sanitized

[xjiang-at-wiris]

@carla-at-wiris I know semantics issue is fixed by adding the allow_mathml_annotation_encodings property. But I think this is a simpler and more intuitive way to solve it.

How do you think?

[jgonzalez-at-wiris]

👀