This is a followup to #5543 that utilizes the new disambiguation to resolve #5500.

Essentially this allows Array.splice to DWIM for the following syntax:

# applies to all candidate combos for Array.splice, just using '*, *,' as an example   
my @array = <a b c>;
@array.splice(*, *, $[<q e d>]); dd @array
# Mu @array = ["a", "b", "c", ["q", "e", "d"]]
### or 
@array.splice(*, *, $(<e r g o>)); dd @array
# Mu @array = ["a", "b", "c", ("e", "r", "g", "o")]

This syntax is, in my opinion, much more discoverable (and pleasant) than the other means of dealing with "single argument collapse" ([[<h m m>],].

(Note: This PR includes a commit to enable the disambiguation for $())