[REPLCompletions] get completions for `:toplevel`/`:tuple` expressions (#51454)
This allows us to get completions for the following kind of cases:
```julia
julia> some_issue36437 = Some(Issue36437(42));
julia> some_issue36437.value.a, some_issue36437.value.
a
b
c
julia> some_issue36437.value.a; some_issue36437.value.
a
b
c
```