patch 8.2.1540: the user cannot try out emoji character widths

Problem:    The user cannot try out emoji character widths.
Solution:   Move the emoji script to the runtime/tools directory.

runtime/tools/emoji_list.vim

@@ -0,0 +1,23 @@
+" Script to fill the window with emoji characters, one per line.
+" Source this script: :source %
+
+if &modified
+  new
+else
+  enew
+endif
+
+" Use a compiled Vim9 function for speed
+def DoIt()
+  let lnum = 1
+  for c in range(0x100, 0x1ffff)
+    let cs = nr2char(c)
+    if charclass(cs) == 3
+      setline(lnum, '|' .. cs .. '| ' .. strwidth(cs))
+      lnum += 1
+    endif
+  endfor
+enddef
+
+call DoIt()
+set nomodified