Make TAB-completion behave as SHIFT-TAB in REPL except for ?(x,y) syntax

[Liozou]

#38791 introduced the ?(x,y)TAB syntax in REPL for discovering methods accepting given argument types. To avoid showing irrelevant suggestions, it was decided that only methods having at least one of their argument annotated by a non-Any type would be shown when using a simple TAB, and all methods would only be shown when using SHIFT-TAB. For reference, check the NEWS entry or the documentation.

However, this behavior of TAB vs SHIFT-TAB affects not only the ?(x,y)TAB syntax, but also the usual REPL method completion. Consider:

julia> foo(a; kwarg) = kwarg - a;

julia> foo( #TAB -> nothing

julia> foo( #SHIFT-TAB
foo(a; kwarg) in Main at REPL[1]:1

I'm not sure this behavior is desired, nor actually intentional. In particular, the docs were not updated: the entry on max([1, 2], #TAB completion currently does not show any of the proposed suggestions since they don't have a non-Any argument type.

This PR restores the previous behavior of simple TAB (identical to the current SHIFT-TAB) for everything but the ?(x,y) syntax, where the distinction is kept. Alternatively, if the current behavior is preferred, at least the docs should be updated to make people think of using SHIFT-TAB instead of TAB. In any case, I think it's good to have this PR open to weigh the opinions of everyone.

[Liozou]

An implementation note: there were different options but the simplest seemed to add an optional argument to completions. This might need updating FuzzyCompletions.jl and julia-vscode's completion file and others, I'm not really sure.

[Liozou]

Sorry to bother you directly @timholy but since you authored #38791, would you mind checking whether the issue described above was intentional?
If so, I can close this PR, I'll open another one to indicate in the docs that SHIFT-TAB should be used for usual method completion as well in order to have all the results appear.

[timholy]

Not an intended consequence, thanks for fixing!

[Liozou]

No problem, thanks!