runtime(vim): Update base syntax, improve function call highlighting

- Match more function calls.
- Contain function call syntax groups.
- Improve differentiation between Ex commands and builtin functions with
  the same name.  Remove special cases.  Command modifiers are not
  currently well differentiated from functions.

closes: #17712

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

runtime/syntax/testdir/dumps/vim_ex_execute_02.dump

@@ -17,4 +17,4 @@
 |"+0#0000e05&| |:|e|x|e|c|u|t|e| |w|i|t|h|o|u|t| |{|e|x|p|r|}| +0#0000000&@49
 |e+0#af5f00255&|x|e|c|u|t|e||+0#0000000&| |e+0#af5f00255&|c|h|o| +0#0000000&|"+0#e000002&|F|o@1|"| +0#0000000&@55
 @75
-@57|3|7|,|7| @9|7|5|%| 
+@57|3|7|,|7| @9|7@1|%|