patch 9.1.0465: missing filecopy() function

Problem:  missing filecopy() function
Solution: implement filecopy() Vim script function
          (Shougo Matsushita)

closes: #12346

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/todo.txt b/runtime/doc/todo.txt
index 7491b06..c37a1d4 100644
--- a/runtime/doc/todo.txt
+++ b/runtime/doc/todo.txt
@@ -1,4 +1,4 @@
-*todo.txt*      For Vim version 9.1.  Last change: 2024 May 11
+*todo.txt*      For Vim version 9.1.  Last change: 2024 Jun 03
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -82,8 +82,6 @@
 wrapping line that makes the display scroll up may scroll much more than
 needed, thus jump-scrolling. (part of issue 12411)
 
-Add filecopy() ?  #12346
-
 Implement foreach()  PR  #12166
 
 Errors when running tests with valgrind:
@@ -4242,7 +4240,6 @@
 	base64enc()		base 64 encoding
 	base64dec()		base 64 decoding
 	attributes()		return file protection flags "drwxrwxrwx"
-	filecopy(from, to)	Copy a file
 	shorten(fname)		shorten a file name, like home_replace()
 	perl(cmd)		call Perl and return string
 	inputrl()		like input() but right-to-left