feat(highlight): add StatusLineTerm and StatusLineTermNC groups

These highlight groups are used for the statusline in :terminal windows.
By default they link to StatusLine and StatusLineNC (respectively), so
there is no visual difference unless a colorscheme defines these groups
separately.

runtime/doc/syntax.txt

@@ -5107,6 +5107,11 @@ SpellRare	Word that is recognized by the spellchecker as one that is
 StatusLine	Status line of current window.
 							*hl-StatusLineNC*
 StatusLineNC	Status lines of not-current windows.
+							*hl-StatusLineTerm*
+StatusLineTerm	Status line of |terminal| window.
+							*hl-StatusLineTermNC*
+StatusLineTermNC
+		Status line of non-current |terminal| window.
 							*hl-TabLine*
 TabLine		Tab pages line, not active tab page label.
 							*hl-TabLineFill*

src/nvim/highlight.h

@@ -78,6 +78,8 @@ EXTERN const char *hlf_names[] INIT( = {
   [HLF_CU] = "Cursor",
   [HLF_BTITLE] = "FloatTitle",
   [HLF_BFOOTER] = "FloatFooter",
+  [HLF_TS] = "StatusLineTerm",
+  [HLF_TSNC] = "StatusLineTermNC",
 });
 
 EXTERN int highlight_attr[HLF_COUNT + 1];     // Highl. attr for each context.

src/nvim/highlight_defs.h

@@ -125,6 +125,8 @@ typedef enum {
   HLF_CU,         ///< Cursor
   HLF_BTITLE,     ///< Float Border Title
   HLF_BFOOTER,    ///< Float Border Footer
+  HLF_TS,         ///< status line for terminal window
+  HLF_TSNC,       ///< status line for non-current terminal window
   HLF_COUNT,      ///< MUST be the last one
 } hlf_T;
 

src/nvim/highlight_group.c

@@ -171,6 +171,8 @@ static const char *highlight_init_both[] = {
   "default link PmenuKindSel     PmenuSel",
   "default link PmenuSbar        Pmenu",
   "default link Substitute       Search",
+  "default link StatusLineTerm   StatusLine",
+  "default link StatusLineTermNC StatusLineNC",
   "default link TabLine          StatusLineNC",
   "default link TabLineFill      TabLine",
   "default link TermCursorNC     NONE",

test/functional/ui/cursor_spec.lua

@@ -250,7 +250,7 @@ describe('ui/cursor', function()
         m.attr = { background = Screen.colors.DarkGray }
       end
       if m.id_lm then
-        m.id_lm = 69
+        m.id_lm = 71
       end
     end