runtime(vim): Update syntax file, improve :substitute matching (#14093)

- Differentiate between :substitute and substitute(), fixes #13883.
- Match all allowed :substitute delimiters.
- Remove leading context from :substitute matches.

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

runtime/syntax/testdir/input/vim_ex_substitute.vim

@@ -0,0 +1,86 @@
+substitute/foo/bar/&
+substitute/foo/bar/cegiInp#lr
+
+snomagic/foo/bar/&
+snomagic/foo/bar/cegiInp#lr
+
+smagic/foo/bar/&
+smagic/foo/bar/cegiInp#lr
+
+:substitute/foo/bar/&
+:substitute/foo/bar/cegiInp#lr
+
+:snomagic/foo/bar/&
+:snomagic/foo/bar/cegiInp#lr
+
+:smagic/foo/bar/&
+:smagic/foo/bar/cegiInp#lr
+
+call Foo() | substitute/foo/bar/&
+call Foo() | substitute/foo/bar/cegiInp#lr
+
+call Foo() | snomagic/foo/bar/&
+call Foo() | snomagic/foo/bar/cegiInp#lr
+
+call Foo() | smagic/foo/bar/&
+call Foo() | smagic/foo/bar/cegiInp#lr
+
+let foo = str->substitute(str, pat, sub, flags)
+
+function Foo()
+  substitute/foo/bar/
+  let bar = str->substitute(str, pat, sub, flags)
+endfunction
+
+def Foo()
+  substitute/foo/bar/
+  let bar = str->substitute(str, pat, sub, flags)
+enddef
+
+" various delimiters
+
+s!/!//! " comment
+" s"/"//" " comment (works but disallowed)
+s#/#//# " comment
+s$/$//$ " comment
+s%/%//% " comment
+s&/&//& " comment
+s'/'//' " comment
+" FIXME - matches vimUserFunc
+" s(/(//( " comment
+s)/)//) " comment
+s*/*//* " comment
+s+/+//+ " comment
+s,/,//, " comment
+s-/-//- " comment
+s././/. " comment
+s/X/XX/ " comment
+s:/://: " comment
+s;/;//; " comment
+s</<//< " comment
+s=/=//= " comment
+s>/>//> " comment
+s?/?//? " comment
+s@/@//@ " comment
+s[/[//[ " comment
+" s\/\//\ " comment (disallowed)
+s]/]//] " comment
+s^/^//^ " comment
+s_/_//_ " comment
+s`/`//` " comment
+s{/{//{ " comment
+" s|/|//| " comment (disallowed)
+s}/}//} " comment
+s~/~//~ " comment
+
+
+" Issue #13883
+
+str[s]
+str(s)
+
+def Test()
+  str[s]
+  str(s)
+enddef
+