Add Packed*Array(<elements>) literals to GDScript

[dalexeev]

GDScript does not support PackedInt32Array(1, 2, 3) syntax, only PackedInt32Array([1, 2, 3])¹. At the same time, .tscn, .tres, var_to_str, etc. do not use [].

print(var_to_str(PackedInt32Array([1, 2, 3]))) # PackedInt32Array(1, 2, 3)

Footnotes

1. Does this mean that the Array is created first, and then it is converted to Packed*Array?
   Possibly related: GDScript 2.0: Packed arrays are not considered constant expressions godot#67873. ↩

[Calinou]

This might be implementable, but only if Variant constructors support using vararg. The performance difference of using this on medium/large-sized arrays should also be checked.

[dalexeev]

Even if Variant doesn't support it, we could recognize it at the GDScript parser/tokenizer (Packed*Array literals).