fix(options): mark winhighlight as list style (#19477)

Also add missing fcs, lcs and winhighlight to list of key-value options for `vim.opt`.

Co-authored-by: ii14 <ii14@users.noreply.github.com>

runtime/lua/vim/_meta.lua

@@ -198,7 +198,10 @@ end
 --                  Can be done in a separate PR.
 local key_value_options = {
   fillchars = true,
+  fcs = true,
   listchars = true,
+  lcs = true,
+  winhighlight = true,
   winhl = true,
 }
 

src/nvim/options.lua

@@ -2868,7 +2868,8 @@ return {
     {
       full_name='winhighlight', abbreviation='winhl',
       short_desc=N_("Setup window-local highlights");
-      type='string', scope={'window'},
+      type='string', list='onecomma', scope={'window'},
+      deny_duplicates=true,
       alloced=true,
       redraw={'current_window'},
       defaults={if_true=""}

test/functional/api/vim_spec.lua

@@ -2732,8 +2732,8 @@ describe('API', function()
 
     it('should have information about window options', function()
       eq({
-        allows_duplicates = true,
-        commalist = false;
+        allows_duplicates = false,
+        commalist = true;
         default = "";
         flaglist = false;
         global_local = false;