Vlv2TbltDevicePkg: Add the missing BootManagerMenuApp

* BootManagerMenuApp wasn't imported so the Boot Device Menu never showed
  correctly.

* Also fix the description of UiApp.
  In the "Rule.Common.UEFI_APPLICATION.UI" section, it intends to change
  the description of UiApp to "Enter Setup" to make the boot option
  self-explaining in the Boot Menu. But this didn't happen since the rule
  wasn't assigned to UiApp correctly, so the Boot Menu only showed "UiApp"
  which is not understandable to users. This patch adds "RuleOverride = UI"
  to UiApp.inf to change the description.

v2:
  Update the description

Cc: Zailiang Sun <zailiang.sun@intel.com>
Cc: Yi Qian <yi.qian@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>