patch 8.2.1138: Vim9: return type of copy() and deepcopy() is any

Problem:    Vim9: return type of copy() and deepcopy() is any.
Solution:   Use type of the argument.

src/testdir/test_vim9_func.vim

@@ -893,6 +893,22 @@ def Test_getloclist_return_type()
   assert_equal(#{items: []}, d)
 enddef
 
+def Test_copy_return_type()
+  let l = copy([1, 2, 3])
+  let res = 0
+  for n in l
+    res += n
+  endfor
+  assert_equal(6, res)
+
+  let dl = deepcopy([1, 2, 3])
+  res = 0
+  for n in dl
+    res += n
+  endfor
+  assert_equal(6, res)
+enddef
+
 def Line_continuation_in_def(dir: string = ''): string
     let path: string = empty(dir)
             \ ? 'empty'