Shortcut discoverability should be improved in GT

[botwhytho]

A proposed solution below. Anything like this functionality would help people with learning shortcuts. Using this in my image I learned about many shortcuts I didn't even know about like adding a Breakpoint (that one can be added through a context menu as well but doesn't apply to most keyboard shortcuts).

addShortcutsHelperShortcut
	| rootElement shortcut |
	rootElement := (GtWorld spaceWithId: GtWorld defaultId do: #yourself) root.
	shortcut := BlShortcutWithAction new
			name: 'Show List of Keyboard Shortcuts';
			description: 'Show list of keyboard shortcuts in the currently focused element';
			combination: (BlKeyCombinationBuilder new primary key: BlKeyboardKey slash) build;
			action: [ :aBlShortcutEvent :aBlShortcutWithAction | 
				| focused pager shortcuts |
				focused := rootElement deepestFocusedChild ifNil: [ rootElement ].
				pager := focused
						withAllParentsDetect: [ :each | each isKindOf: GtPager ]
						ifFound: #yourself
						ifNone: [ nil ].
				shortcuts := focused gtShortcutsFor: GtPhlowEmptyView new.
				pager
					ifNil: [ GtInspector openOn: shortcuts from: rootElement ]
					ifNotNil: [ focused phlow spawnObject: shortcuts ] ].
	rootElement addShortcut: shortcut

Above is an MVP, this could show up as a context menu or in some other way.

The primary + slash in an american QWERTY keyboard is the same key as the question mark. I've seen other software show keyboard shortcut help when typing Shift + ?, so trying to resemble that but using primary so as to not type / or ? if in an editor. Open to other keyboard shortcuts but this is close to one I have already seen in other places so maybe others already have the notion/muscle memory that such a shortcut would have a similar action in GT.

I've tested this and works as expected in coders, pharo snippets, text snippets, from the spotter, etc.