Add PCD for selecting terminal type at build time

Add PCD for selecting terminal type at build time

Add a fixed pointer PCD to allow build-time selection of VT100 or TTY terminal
type.  The default remains VT100 emulation.
Add support for building the ARM QEMU platforms with the TTY terminal
with the "-D TTY_TERMINAL" build option.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
[Roy Franz: minor edits: add TtyTerminal GUID, rename LINUX_TERMINAL to TTY_TERMINAL]
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Roy Franz <roy.franz@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17898 6f19259b-4bc3-4df7-8a09-765794883524