runtime(vim): Update base-syntax, improve function definition highlighting (#14203)

Improve function definition highlighting.

- Match bang and function modifiers - abort etc.
- Only match valid scope modifiers.
- Match listing commands.
- Don't match ex commands in function names.
- Split function syntax groups into :func and :def subgroups.
- Match Vim9-script parameter and return types.
- Limit legacy-script and Vim9-script comments to :func and :def
  definitions, respectively.

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

runtime/syntax/testdir/dumps/vim_ex_syntax_09.dump

@@ -11,9 +11,9 @@
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 |"+0#0000e05&| @2|"+0#e000002&|c|l|u|s|t|e|r|"| +0#0000e05&|s|h|o|u|l|d| |n|o|t| |b|e| |h|i|g|h|l|i|g|h|t|e|d| |o|u|t|s|i|d|e| |o|f| |:|s|y|n|t|a|x| |c|o|m@1|a|n|d|s| +0#0000000&@7
 @75
-|f+0#af5f00255&|u|n|c|t|i|o|n|!+0#0000000&| |s+0#e000e06&|:|C+0#0000000&|o|n|t|a|i|n|e|d|G|r|o|u|p|(+0#e000e06&|)| +0#0000000&@46
+|f+0#af5f00255&|u|n|c|t|i|o|n|!| +0#0000000&|s+0#e000e06&|:|C+0#0000000&|o|n|t|a|i|n|e|d|G|r|o|u|p|(+0#e000e06&|)| +0#0000000&@46
 | +0#0000e05&@1|"| |.@2| +0#0000000&@67
-@2|f+0#af5f00255&|o|r| +0#0000000&|c|l|u|s|t|e|r| |i+0#af5f00255&|n| +0#0000000&|[|'+0#e000002&|m|a|r|k|d|o|w|n|H|i|g|h|l|i|g|h|t|_|z|s|h|'|,+0#0000000&| |'+0#e000002&|z|s|h|'|]+0#0000000&| @25
+@2|f+0#af5f00255&|o|r| +0#0000000&|c+0#00e0e07&|l|u|s|t|e|r| +0#0000000&|i+0#af5f00255&|n| +0#0000000&|[|'+0#e000002&|m|a|r|k|d|o|w|n|H|i|g|h|l|i|g|h|t|_|z|s|h|'|,+0#0000000&| |'+0#e000002&|z|s|h|'|]+0#0000000&| @25
 | +0#0000e05&@3|"| |.@2| +0#0000000&@65
 @2|e+0#af5f00255&|n|d|f|o|r| +0#0000000&@66
 | +0#0000e05&@1|"| |.@2| +0#0000000&@67