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_03.dump

@@ -5,9 +5,8 @@
 @75
 >"+0#0000e05&| |I|s@1|u|e| |#|9@1|8|7| |(|p|a|r|e|n|t|h|e|s|i|s|e|d| |a|r|g|u|m|e|n|t| |-| |n|o|t| |a| |f|u|n|c|t|i|o|n| |c|a|l@1|)| +0#0000000&@14
 @75
-|"+0#0000e05&| +0#0000000&|F+0#0000001#ffff4012|I|X|M|E|:+0#e000e06#ffffff0| +0#0000e05&|e|x|e|c|u|t|e| |i|s| |e|x| |c|o|m@1|a|n|d| |n|o|t| |b|u|i|l|t|i|n| |f|u|n|c|t|i|o|n| +0#0000000&@23
 |l+0#af5f00255&|e|t| +0#0000000&|f+0#00e0e07&|o@1| +0#0000000&|=+0#af5f00255&| +0#0000000&|{+0#e000e06&|'+0#e000002&|a|r|g|'|:+0#0000000&| |"+0#e000002&|c|a|l@1| |F|o@1|(|)|"|}+0#e000e06&| +0#0000000&@43
-|e+0#00e0e07&|x|e|c|u|t|e| +0#0000000&|(+0#e000e06&|f+0#00e0e07&|o@1|.+0#af5f00255&|a+0#00e0e07&|r|g|)+0#e000e06&| +0#0000000&@57
+|e+0#af5f00255&|x|e|c|u|t|e| +0#0000000&|(+0#e000e06&|f+0#00e0e07&|o@1|.+0#af5f00255&|a+0#00e0e07&|r|g|)+0#e000e06&| +0#0000000&@57
 @75
 |~+0#4040ff13&| @73
 |~| @73
@@ -17,4 +16,5 @@
 |~| @73
 |~| @73
 |~| @73
+|~| @73
 | +0#0000000&@56|5@1|,|1| @9|B|o|t|