Modifying ResolvedKeybindingItem to support multiple chords

[toumorokoshi]

A continuation of #65826, this handles one of the TODO items thus far (ResolvedKeybindingItem).

Before I move forward I wanted to do a quick preliminary discussion. @alexandrudima as you mentioned, keybindingResolver.ts looks to need a significant refactor to make this work and keep the code clean.

My thoughts from a high-level:
Instead of having a map of <key, [ResolvedKeybindingItem]> pairs, instead have a nested map of Keys to a multiple [ResolvedKeybindingItem] (multiple because there could multiple matches that satisfy different contexts). E.g. ctrl-x ctrl-z would look like:

{
    "ctrl-x": {
        "ctrl-z": [ResolvedKeybindingItem]
    }
}

I think this would be faster than a list as you wouldn't have to iterate through all options and check if the keychord matches. Otherwise this will probably be noticeable with really deep keychords.

After that, it's a matter of ensuring that the existing rules around overrides and context matches works as expected.

Does that sound ok?

[toumorokoshi]

quick shout out to #6966 to note there is progress being made!

[alexdima]

I've left TODO@chords inside keybindingsResolver.ts where assumptions are made. I suggest we merge more often since reviewing is a lot of work... I am not 100% sure about the data-structure. Please give me some more time to think about it.

[toumorokoshi]

@alexandrudima sounds good. Do you want to let me know when you have an idea about what to do next? Or should I take a stab at a PR to start the discussion?

[toumorokoshi]

@alexandrudima revisitting this. Have you thought more about the data structure? Would a PR to start the conversation be helpful? Feels like we're close, would love to get this moving forward.