Add a command to activate next panel

[mlucool]

The main work area is great for having tabs in multiple groupings. Can we add a command with a keyboard shortcut active the next panel (sorry if my terminology is off).

This would toggle between 5 and 7 in this screenshot:

Using application:activate-next-tab would have togged 6 next.

[jasongrout]

That sounds like a great idea to have a "jump to next panel" - of course which panel is next in a complicated layout might not be obviously the same for everyone, but I suppose any reasonable cycling is better than nothing.

Likely this would be a command implemented next to the activate next tab command:

jupyterlab/packages/application-extension/src/index.tsx

Lines 530 to 535 in 4336b1a

	commands.addCommand(CommandIDs.activateNextTab, {
	label: 'Activate Next Tab',
	execute: () => {
	shell.activateNextTab();
	}
	});

and likely it would do something very similar - executing a shell method. The shell method could go next to the existing one and be similar:

jupyterlab/packages/application/src/shell.ts

Line 438 in 4336b1a

activateNextTab(): void {

[jasongrout]

Setting as a good first issue. Let us know if you'd like to have a go at doing this.

[tgeorgeux]

Closing Via #7673