Bugfix: Fix dcc.Markdown issues with <dccLink />

[KoolADE85]

dcc.Markdown used dependencies that were fundamentally incompatible with our <dccLink /> implementation + React 19 deps.
This PR rewrites the Markdown component to use markdown internals that are compatible.
Along the way, it's converted to Typescript.

dcc.Link is also converted to Typescript (no functional change) so as not to introduce TS compile errors.

Testing notes:

• while this is a rewrite, I intend for this to be included in a minor release: You can compare against the old Markdown.react.js implementation for parity
• I added plenty of missing integration tests

Fixes #3951

Contributor Checklist

• I have run the tests locally and they passed. (refer to testing section in contributing)
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

optionals

• I have added entry in the CHANGELOG.md
• If this PR needs a follow-up in dash docs, community thread, I have mentioned the relevant URLS as follows
  • this GitHub #PR number updates the dash docs
  • here is the show and tell thread in Plotly Dash community

[sonarqubecloud]

Quality Gate passed

Issues
23 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.6% Duplication on New Code

See analysis details on SonarQube Cloud