Merge main-next to main to enable attestation setup (#51)

* Add attestation setup script

* Check script is run with root privileges

* Add trust authority client in setup guest script

* Add build-essential to compile tdx-attest

* Add remote attestation setup and how to use instruction (#42)

Signed-off-by: Bun K Tan <bun.k.tan@intel.com>

* Validate and clean up attestation instructions (#48)

* Validate and clean up attestation instructions

* Use more explicit naming of attestation scripts

* Remove sudo from commands in guest

* Remove useless script setup-attestation.sh

* Use tdx-release PPA that contains released components (#49)

* Improve attestation setup script (#50)

* setup-attestation-host.sh : do not set user and group for /dev/sgx_provision

the udev rules will take care of it

* Remove README section on use_secure_cert

with the version 1.18-0ubuntu2 of libsgx-dcap-default-qpl
the use_secure_cert is set to false by default

* Add reboot instruction in README

after the setup script run for attestation, we need to reboot
to have the right owner & group for /dev/sgx_provision (from udev rule)

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Signed-off-by: Bun K Tan <bun.k.tan@intel.com>
Co-authored-by: Ubuntu <ubuntu@sysid-739457.maas>
Co-authored-by: Bun K Tan <bun.k.tan@intel.com>
Co-authored-by: Will French <will.french@canonical.com>