wrapped lines w screen reader

[meganrogge]

Fixes #95428

• when a screen reader is attached, the editor is forced to compute wrapping points using the advanced strategy (the one using the DOM) and without any wrapping indent.
• wrapping is then also enabled in the textarea and the idea is that the textarea's wrapping points will match the editor's wrapping points.
• there are many details to get right, such as the tab size in the textarea, scrolling it such that VoiceOver's thick black box lines up with the editor content, turning wrapping off when IME is active, etc.

[alexdima]

I've extracted some of the commits to #164030