ArmPlatformPkg/Bds: Upgrade the BDS to be more conformed to the UEFI Specification

ArmPlatformPkg/Bds: Upgrade the BDS to be more conformed to the UEFI Specification

The UEFI Specification defines some requirement related to the Boot Manager.
This new version of the BDS support most of the features:
- TimeOut, BootNext, BootOrder, Boot### environment variable for boot device selection
- ConOut. ConIn, ConErr environment variables for console intialization
- Boot EFI application defined by a Device Path
- Support removable devices
- Support FileSystem, MemMap, PXE and TFTP boot devices

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11800 6f19259b-4bc3-4df7-8a09-765794883524