Maintainers: rename the OVMF SEV subsystem to "Confidential Computing"

Maintainers: rename the OVMF SEV subsystem to "Confidential Computing"

The implementation of Intel TDX for OVMF has begun (TianoCore#3249).
Generalize the OVMF SEV section in "Maintainers.txt" to "Confidential
Computing". Add Jiewen Yao and Min Xu to the list of reviewers. Sort the
reviewer list alphabetically, for easier extension in the future.

After the rename, restore the alphabetical ordering between subsystem
titles in "Maintainers.txt".

TDX-related pathnames should be listed in this subsystem (with "F:"
patterns) in the future.

Cc: Andrew Fish <afish@apple.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3249
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20210310185649.19801-3-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Jiewen Yao <jiewen.yao@intel.com>
Acked-by: Leif Lindholm <leif@nuviainc.com>
Acked-by: James Bottomley <jejb@linux.ibm.com>
Acked-by: Min Xu <min.m.xu@intel.com>