PLGEDT-46 Add a chained code assistant processor implementation
PLGEDT-46 Port the web editors to jseditor
Fix for completion not updating when typing

The completion starting point offset was defined popup creation and
never changed after.
Made sure to recompute it at each update.
Merge pull request #333 from mleduque/PLGEDT-46

PLGEDT-46 Use jseditor for web (html and js)