Add CodeMirror editor signals (selection, focus, viewport, geometry) and reveal_line#5984

Jepson2k wants to merge 2 commits intozauberzeug:mainzauberzeug/nicegui:mainfrom

Jepson2k:cm-cursor-save-revealJepson2k/nicegui:cm-cursor-save-revealCopy head branch name to clipboard