MdeModulePkg/BM: Update boot options on device change

Register an event to trigger when a block device is added or removed
that will update the list of boot options. Use a refreshguid to force
the form to display the changes if it already open.

MdeModulePkg/Library/BootManagerUiLib/BootManager.h

@@ -46,6 +46,11 @@ typedef struct {
   0x847bc3fe, 0xb974, 0x446d, {0x94, 0x49, 0x5a, 0xd5, 0x41, 0x2e, 0x99, 0x3b} \
   }
 
+#define BOOT_MANAGER_REFRESH_GUID \
+  { \
+    0x7648C827, 0xBE32, 0x44D2, { 0xA1, 0x33, 0xF1, 0x7F, 0x93, 0x76, 0xC7, 0x00 } \
+  }
+
 #define BOOT_MANAGER_FORM_ID     0x1030
 
 #define LABEL_BOOT_OPTION        0x00