[c&s] merge create action dialog with cmd-k

[zhenyasav]

• currently the create action dialog is a standalone thing, specific to the navtree and is integrate w/ cmd-k via a hack
• the create action (and action groups generally) should be natively navigable within cmd-k
• the create action should also be a general purpose tool that other plugins can hook into
  • for example rather than special stack creators, adding to a stack should open the create dialog and just ensure that created object is added to the underlying collection
  • another possible use case for this would be autocomplete for document linking (though an inline autocomplete may prove a better ux in that case)

[wittjosiah]

There's quite a lot that will need to be done in order to accomplish this:

• keyboard and graph stuff either needs to be fully integrated or decoupled, I think I'd lean towards decoupled
• if they're decoupled then the keyboard contexts can be added via a graph traversal from a shortcut plugin
• keyboard context is only ever additive, so it doesn't support narrowing the scope by selecting an action group (https://github.com/dxos/dxos/pull/5063 is a UI-level hack around this limitation)
• in order to unify the cmd-k and the create actions dialog, clicking on the actions group somehow needs to open the cmd-k. The best solution I have for this is that there's a common shortcuts action defined by the framework that can be fired without coupling other plugins to our specific shortcut plugin
• graph doesn't handle actions groups very elegantly (they're still actions so still require invoke, even though that seems not useful)
• you can't traverse actions in the graph, only nodes
• there's likely incremental changes that could improve the graph, but if we're opening the hood on graph I'd probably want to go down the path Dima and I discussed here https://discord.com/channels/837138313172353095/1110905190661496862/1176488490502979696

[wittjosiah]

The graph changes noted above are now captured by #5696