[Close Others] Fix #6019: Contextual Close Others menu entries

[marcelgerber]

This is for #6019, it makes the Close Others context menu entries contextual so that they are dynamically disabled and enabled.

[TomMalbran]

In this case, all the commands should be disabled, since you can't close other files.

[marcelgerber]

They will be disabled too as the selected entry is both first and last (and only) entry.

[TomMalbran]

Right. Didn't saw that before.

[marcelgerber]

Btw: Is there another handler that is called when (before) opening the context menu of the Working Files? currentDocumentChange is called every time you open another doc and maybe it isn't even called when you re-organize your Working Set order or do something similar. So it would be cool if there's another handler.

[njx]

Assigning to @JeffryBooher

[JeffryBooher]

Nominating for Sprint 35

[JeffryBooher]

Looks good...Merging

[marcelgerber]

I forgot about this PR, but in the meantime I found #5952. I won't say any of these is better or worse, but a difference worth mentioning is using $(workingSetCmenu).on("beforeContextMenuOpen") instead of currentDocumentChange.
I'll just create another PR to get this change in.