notebook toolbar rewrite. Adopt WorkbenchToolbar

[Yoyokrazy]

re: #161119

Adopting WorkbenchToolbar into notebooks. Required a rewrite of the complete toolbar, meaning strategies had to be reworked as well.

Features it brings:

• right click to hide items
• right click to reset toolbar to original state (all possible displayed, ignoring hidden secondary actions)

Todo:

• adapt dynamic and label-less strategies to work alongside workbench toolbar.
• "default" renderlabel setting ("notebook.globalToolbarShowLabel": "always") gives workbench functionality, other two labels never + dynamic use older toolbar.
  • this requires reload upon changing label setting

To enable:

• "notebook.experimental.workbenchToolbar": true