feat: add new keybinding "b" to run a command in the focused node (#1024)

doc/nvim-tree-lua.txt

@@ -615,6 +615,7 @@ INFORMATIONS				        *nvim-tree-info*
 - Double right click acts like <C-]>
 - `W` will collapse the whole tree
 - `S` will prompt the user to enter a path and then expands the tree to match the path
+- `.` will enter vim command mode with the file the cursor is on
 
 Defaults to:
 >
@@ -655,7 +656,8 @@ Defaults to:
       { key = "q",                            action = "close" },
       { key = "g?",                           action = "toggle_help" },
       { key = 'W',                            action = "collapse_all" },
-      { key = "S",                            action = "search_node" }
+      { key = "S",                            action = "search_node" },
+      { key = ".",                            action = "run_file_command" }
     }
 <
 The `list` option in `view.mappings.list` is a table of