spdm: Support requester session encryption

Also, fix some small bugs in the aead logic found by the new unittests.

BUG=b:335386464
TEST=spdm unittests

Change-Id: If520c40b506ee21cd1bd0853bf427fe3e75eaf87
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/spdm/+/5475527
Tested-by: Howard Yang <hcyang@google.com>
Reviewed-by: Vadim Sukhomlinov <sukhomlinov@google.com>
Commit-Queue: Howard Yang <hcyang@google.com>
6 files changed