Potentially remove -ms-high-contrast

I have re-rolled the patch for D11 and raised MR. Updated TODO items in the Issue Summary. Please check if it's fine.

Don't believe accessibility is needed since this is now dropping IE code.

Hiding patches for MR.

left a comment on MR.

Feedback appears addressed

No-one responded to @longwave in #6, that should have happened before this was worked on and marked RTBC.

It looks like we should be replacing the media selector with https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-contrast rather than just removing these styles, someone who knows CSS/accessibility things more should confirm though.

Came across this issue: https://www.drupal.org/project/drupal/issues/3167032 → , talking about -ms-high-contrast too.

This is now a depreciated tag https://blogs.windows.com/msedgedev/2024/04/29/deprecating-ms-high-contr...

So yes, we should remove this and rebuild the functionality with The forced-colors media query.

Updated the title and IS to reflect that the code must be converted to use forced-colors rather than removed.

RE @longwave's comment, #6:

I suggest converting background image cases to mask-image or mask using the original (full-color) image and using the appropriate system-color as the background.

There are many examples of the technique in Claro. I linked to a couple in the IS.