[BOUNTY #4774] Add VFS frontend browser implementation

- Add menu_vfs_browser.c for VFS file browsing
- Add menu_vfs_browser.h for function declarations
- Update Makefile.common to include new source

Ref: #4774

Author: 龙虾机器人

Makefile.common

@@ -588,6 +588,7 @@ ifeq ($(HAVE_LIBRETRODB), 1)
 
    ifeq ($(HAVE_MENU), 1)
       OBJ += menu/menu_explore.o \
+             menu/menu_vfs_browser.o \
              tasks/task_menu_explore.o
    endif
 endif