Make callable-related MethodError messages more descriptive

[jishnub]

Addresses #57807 to some extent, although the error message may be improved further.

On nightly,

julia> stack(1:3, 1:3)
ERROR: MethodError: objects of type UnitRange{Int64} are not callable
Use square brackets [] for indexing an Array.
The object of type `UnitRange{Int64}` exists, but no method is defined for this combination of argument types when trying to treat it as a callable object.

The second sentence seems unrelated to the first, and the source of the error remains unclear from the message.

This PR makes the message more verbose, and provides pointers.

julia> stack(1:3, 200)
ERROR: MethodError: objects of type UnitRange{Int64} are not callable.
In case you did not try calling it explicitly, check if a UnitRange{Int64} has been passed as an argument to a method that expects a callable instead.
In case you're trying to index into the array, use square brackets [] instead of parentheses ().
The object of type `UnitRange{Int64}` exists, but no method is defined for this combination of argument types when trying to treat it as a callable object.