[Feature] Encapsulate config logic (#1338)

* Define core/builtins, streamline status_color interface

* Encapsulate configuration in its own module

* Add fallback to lv-config.lua

* Rectify settings loading order to allow overriding vim options

* Move default-config into config/ module

* replace uv.fs_stat with utils.is_file

lua/core/dashboard.lua

@@ -1,6 +1,6 @@
 local M = {}
 
-M.config = function()
+M.config = function(config)
   lvim.builtin.dashboard = {
     active = false,
     on_config_done = nil,
@@ -47,7 +47,7 @@ M.config = function()
       },
       e = {
         description = { "  Configuration      " },
-        command = ":e " .. USER_CONFIG_PATH,
+        command = ":e " .. config.path,
       },
     },