Fixes microsoft/monaco-editor#1378: Convert view coordinates to model coordinates in getTargetAtClientPoint

Fixes #83150: Handle case where the mouse is hitting the textarea when the textarea is rendered at the cursor

Fixes #85817

This fixes unintentional duplications of words, such as `the the`, and
`can can` etc. I also take the chance to make a few wording tweaks to
avoid suspicious duplications.

#81574

When the font scale is small enough, using other ASCII characters for characters outside the supported ASCII range is preferrable.

Fixes #84264