BREAKING Change for statusline_separator & tabufline overriders

moved statusline & tabufline into a new plugin to keep the base config clean and fix issues like (#1307)

lua/core/default_config.lua

@@ -20,19 +20,6 @@ M.ui = {
    theme_toggle = { "onedark", "one_light" },
    theme = "onedark", -- default theme
    transparency = false,
-
-   statusline = {
-      separator_style = "default", -- default/round/block/arrow
-      config = "%!v:lua.require('ui.statusline').run()",
-      override = {},
-   },
-
-   -- lazyload it when there are 1+ buffers
-   tabufline = {
-      enabled = true,
-      lazyload = true,
-      override = {},
-   },
 }
 
 M.plugins = {