Stabilize active terminal APIs

related to #60163

Support odd indentation sizes (fixes #17639)

Fixes #47537

Use our own version of markdown named headers. This fixes some bugs around handling duplicate headers

Fixes #59711

For a md document:

```md
# a

# a

- [a](#a)
- [next a](#a-1)
```

You can now click on the second link in the editor to navigate to the second `a` header. It is identified by being suffixed with `-1`.

Fixes #60204

Fixes #58357

Add experimental terminal buffer line implementation setting

* adding ability to set checked state for menu item at registration

* address feedback

Increase max-width for find-widget in narrow view

Fixes #60155

The css3 `transform` and `transition` properties are now widely supported. I do not believe we need to ship vendor prefixed rules for these anymore