runtime(vim): Update base-syntax, improve :mark and :substitute highlighting

- Match full :mark and :k commands.
- Match 2 and 3 letter :s repeat commands.
- Match :s [count] argument.

closes: #17408

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

runtime/syntax/testdir/input/vim_ex_substitute.vim

@@ -1,3 +1,6 @@
+" Vim :substitute command
+
+
 substitute/foo/bar/&
 substitute/foo/bar/cegiInp#lr
 
@@ -37,6 +40,7 @@ def Foo()
   let bar = str->substitute(str, pat, sub, flags)
 enddef
 
+
 " various delimiters
 
 s!/!//! " comment
@@ -111,6 +115,67 @@ s//{string}/
 s //{string}/
 
 
+" Repeat commands
+
+s
+:s
+s 42
+:s 42
+s42
+:s42
+
+s cegiInp#lr
+:s cegiInp#lr
+s cegiInp#lr42
+:s cegiInp#lr42
+s cegiInp#lr 42
+:s cegiInp#lr 42
+
+sg
+:sg
+sgi
+:sgi
+sg 42
+:sg 42
+sgi 42
+:sgi 42
+sg42
+:sg42
+sgi42
+:sgi42
+
+" FIXME
+&
+&&
+~
+~&
+
+" FIXME
+&cegiInp#lr
+&&cegiInp#lr
+~cegiInp#lr
+~&cegiInp#lr
+
+" 2 and 3 letter repeat-previous variants
+
+:sc  | :sce | :scg | :sci | :scI | :scn | :scp | :scl |
+:sgc | :sge | :sg  | :sgi | :sgI | :sgn | :sgp | :sgl | :sgr
+:sic | :sie |      | :si  | :siI | :sin | :sip |      | :sir
+:sIc | :sIe | :sIg | :sIi | :sI  | :sIn | :sIp | :sIl | :sIr
+:src |      | :srg | :sri | :srI | :srn | :srp | :srl | :sr
+
+
+" exceptions
+:scr  " is  `:scriptnames`
+:se   " is  `:set`
+:sig  " is  `:sign`
+:sil  " is  `:silent`
+:sn   " is  `:snext`
+:sp   " is  `:split`
+:sl   " is  `:sleep`
+:sre  " is  `:srewind`
+
+
 " Vi compatibility
 
 s\/{string}/