vim-patch:8.1.0706: introduce :redrawtabline #10570

Problem:    Tabline is not always redrawn when something that is used in
            'tabline' changes.
Solution:   Add ":redrawtabline" so that a plugin can at least cause the
            redraw when needed.
e12bab3144

src/nvim/ex_cmds.lua

@@ -2150,6 +2150,12 @@ return {
     addr_type=ADDR_LINES,
     func='ex_redrawstatus',
   },
+  {
+    command='redrawtabline',
+    flags=bit.bor(TRLBAR, CMDWIN),
+    addr_type=ADDR_LINES,
+    func='ex_redrawtabline',
+  },
   {
     command='registers',
     flags=bit.bor(EXTRA, NOTRLCOM, TRLBAR, CMDWIN),