- enable layout code to position panel to the left

For #79144

Currently we duplicate information for the `editor` and `workbench` configuration nodes in a few places. This change extracts some of those to be constants instead

* added split pane options to settings

* moved option to workbench config

* updating description messages

* review changes

* 💄

* working on the left side

* flow direction working

* flow direction

* use menubar visibility to set setting

* hide titlebar on the web

* fix hover feedback

More info: https://github.com/microsoft/vscode/issues/76909#issuecomment-524976250

Fixes #73783

* cleanup modules

* more modules cleanup

* more contribution cleanup