runtime(vim): Update base-syntax, improve :set highlighting

- Match bang, "all" and "termcap" options, and trailing command
  separator "|".
- Highlight set assignment operators.
- Match multiline :set and multiline option values.
- Mention the newer "0o" octal prefix at :help :set=.

closes: #15329

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

runtime/doc/options.txt

@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 9.1.  Last change: 2024 Jul 16
+*options.txt*	For Vim version 9.1.  Last change: 2024 Jul 24
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -76,7 +76,8 @@ achieve special effects.  These options come in three forms:
 :se[t] {option}:{value}
 			Set string or number option to {value}.
 			For numeric options the value can be given in decimal,
-			hex (preceded with 0x) or octal (preceded with '0').
+			hex (preceded with 0x) or octal (preceded with '0' or
+			'0o').
 			The old value can be inserted by typing 'wildchar' (by
 			default this is a <Tab> or CTRL-E if 'compatible' is
 			set). Many string options with fixed syntax and names