Investigate to rewrite workbench layout using grid widget

[bpasero]

Given the introduction of the grid widget, we should explore to use it as the driver for the workbench layout, at least for the parts that are connected via sashes:

• sidebar (left / right)
• panel (bottom / right)
• editor area

Related issues:

• Allow 100% panel width even with the explorer view is open Allow 100% panel width and height #42149
• Provide workbench.panel.location "left" option Provide workbench.panel.location "left" option #37877
• Provide workbench.panel.location "top" option Provide workbench.panel.location "top" option #50984
• Panel and viewlet on right should have a border between them Panel and viewlet on right should have a border between them #37373

Grid widget prerequisites

• allow to mark a specific view in the grid as the one to resize when the outer container grows (this is to make sure the editor area always increases in size if the window gets larger)
• allow to "snap to hide" so that e.g. you can use the mouse to make the sidebar small enough that it hides and move back to show it again

[bpasero]

Some prerequisites for the grid widget before this can happen:

• allow to mark a specific view in the grid as the one to resize when the outer container grows (this is to make sure the editor area always increases in size if the window gets larger)
• allow to "snap to hide" so that e.g. you can use the mouse to make the sidebar small enough that it hides and move back to show it again