Show and take over correction proposals of spellcheck also by keyboard

A keyboard short-cut should be introduced, that makes it possible inside the open segment to open the drop-down that offers proposals from the spell-check via key-board inside the open segment, when the cursor is inside a string marked as an error.

The shortcuts need to be listed in the confluence page of short-cuts.

A tool-tip when hovering with the mouse over a languagetool error in the open segment should tell the user:

EN: Press XY to select proposals or right-click this word. Cursor has to be inside error.

DE: Drücken Sie XY, um Vorschläge auszuwählen oder rechts-klicken Sie auf dieses Wort. Der Cursor muss sich innerhalb des Fehlers befinden.

If this tool-tip interferes with the trackChanges tooltip, the TrackChanges tooltip should be shown or both should be merged to one. What ever is more easy.

Coordinate with Leon and me in advance, how to coordinate this with the new segment editor. And if it makes sense to develop it, before the new editor es ready enough.