runtime(doc,vim): Update base syntax, match full :syntime command

- Use the optional tail command-name spec at :help :syntime.
- Match full :syntime command and highlight args.

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/testdir/input/vim_ex_syntime.vim

@@ -0,0 +1,38 @@
+" Vim :syntime command
+
+
+syntime on
+syntime off
+syntime clear
+syntime report
+
+syntime on | redraw! | syntime report
+
+syntime on     | echo "..."
+syntime on     " comment
+syntime off    | echo "..."
+syntime off    " comment
+syntime clear  | echo "..."
+syntime clear  " comment
+syntime report | echo "..."
+syntime report " comment
+
+
+def Vim9Context()
+  syntime on
+  syntime off
+  syntime clear
+  syntime report
+
+  syntime on | redraw! | syntime report
+
+  syntime on     | echo "..."
+  syntime on     # comment
+  syntime off    | echo "..."
+  syntime off    # comment
+  syntime clear  | echo "..."
+  syntime clear  # comment
+  syntime report | echo "..."
+  syntime report # comment
+enddef
+