Add dozens of new integration tests to the GDScript test suite

This also ignores `.out` files in the file format static checks.

modules/gdscript/tests/scripts/parser/features/for_range.out

@@ -0,0 +1,58 @@
+GDTEST_OK
+0
+1
+2
+3
+4
+
+0
+1
+2
+3
+4
+
+1
+2
+3
+4
+
+1
+0
+-1
+-2
+-3
+-4
+
+2
+4
+6
+-8
+
+true
+false
+
+(10, 20)
+(-30, -40)
+
+H
+e
+l
+l
+o
+_
+U
+n
+i
+c
+ô
+d
+e
+_
+w
+o
+r
+l
+d
+!
+_
+🦄