Platform/DeveloperBox: enable HTTPS boot

Enable support for HTTPS boot by incorporating the TLS DXE driver into
the build, and the driver that permits enrolling the TLS certificates.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>