Migrate options to setup

This migrates and renamed the following options to `nvim_tree.setup` in accordance to nvim-tree migration guide:

* vim.g.nvim_tree_icons -> moved to setup.renderer.icons.glyphs
* setup.auto_close -> feature has been removed
* setup.update_to_buf_dir -> renamed to hijack_directories
* setup.quit_on_open -> moved to setup.actions.open_file
* setup.git_hl -> renamed to highlight_git and moved to setup.renderer
* setup.disable_window_picker -> renamed to window_picker and moved to setup.actions
* setup.root_folder_modifier -> moved to setup.renderer
* setup.show_icons -> moved to setup.renderer.icons.show; removed tree_width

Migration guide: https://github.com/kyazdani42/nvim-tree.lua/issues/674
nvim-tree docs : https://github.com/kyazdani42/nvim-tree.lua/blob/master/doc/nvim-tree-lua.txt

lua/user/nvim-tree.lua

@@ -1,25 +1,5 @@
 -- following options are the default
 -- each of these are documented in `:help nvim-tree.OPTION_NAME`
-vim.g.nvim_tree_icons = {
-  default = "",
-  symlink = "",
-  git = {
-    unstaged = "",
-    staged = "S",
-    unmerged = "",
-    renamed = "➜",
-    deleted = "",
-    untracked = "U",
-    ignored = "◌",
-  },
-  folder = {
-    default = "",
-    open = "",
-    empty = "",
-    empty_open = "",
-    symlink = "",
-  },
-}
 
 local status_ok, nvim_tree = pcall(require, "nvim-tree")
 if not status_ok then
@@ -42,11 +22,10 @@ nvim_tree.setup {
         "dashboard",
         "alpha",
     },
-  auto_close = true,
     open_on_tab = false,
     hijack_cursor = false,
     update_cwd = true,
-  update_to_buf_dir = {
+    hijack_directories = {
         enable = true,
         auto_open = true,
     },
@@ -86,15 +65,40 @@ nvim_tree.setup {
         number = false,
         relativenumber = false,
     },
-  quit_on_open = 0,
-  git_hl = 1,
-  disable_window_picker = 0,
+    actions = {
+        quit_on_open = true,
+        window_picker = { enable = true },
+    },
+    renderer = {
+        highlight_git = true,
         root_folder_modifier = ":t",
-  show_icons = {
-    git = 1,
-    folders = 1,
-    files = 1,
-    folder_arrows = 1,
-    tree_width = 30,
+        icons = {
+            show = {
+                file = true,
+                folder = true,
+                folder_arrow = true,
+                git = true,
             },
+            glyphs = {
+                default = "",
+                symlink = "",
+                git = {
+                    unstaged = "",
+                    staged = "S",
+                    unmerged = "",
+                    renamed = "➜",
+                    deleted = "",
+                    untracked = "U",
+                    ignored = "◌",
+                },
+                folder = {
+                    default = "",
+                    open = "",
+                    empty = "",
+                    empty_open = "",
+                    symlink = "",
+                },
+            }
+        }
+    }
 }