add keyboard shotcuts for collapse/expand rows

[mtanda]

Fixes, #552

I add keyboard shortcuts. Please see following comment.
#7536 (comment)

[bergquist]

Looks good!

You also need to add the shortcuts to https://github.com/grafana/grafana/blob/master/public/app/core/components/help/help.ts

Will merge once help text is added.

[bergquist]

I made the changes myself.

Thanks for contributing!

Closed by 5a30b08

[mtanda]

Sorry, I miss your message.
Thanks for adding the feature!

[perlun]

Anyone else discovering this a few years later (like me), the shortcuts have now changed to this:

grafana/public/app/core/services/keybindingSrv.ts

Lines 281 to 284 in dafc955

	// collapse all rows
	this.bind('d shift+c', () => {
	dashboard.collapseRows();
	});

grafana/public/app/core/services/keybindingSrv.ts

Lines 286 to 289 in dafc955

	// expand all rows
	this.bind('d shift+e', () => {
	dashboard.expandRows();
	});