Store arrays inside of Variant as shared.

[reduz]

Arrays inside of Variant are unique and use reference counting.
When you assign a variant containing a packed array to another, or
when you call non const functions to arrays, this will work even
if the array is inside a dictionary, so they will from now pass
as reference.

The difference with regular variant arrays is that, once passed
to a function in the C++ API, they are no longer shared. This is
required for security and thread safety, as those arrays are
mainly used to pass data back and forth even between threads.

[akien-mga]

OK to merge when CI passes.

[akien-mga]

Thanks!