trousers: Add boundary check functions

Add some safe primitives for parsing TPM_DELEGATE_LABEL,
TPM_DELEGATIONS, TPM_DELEGATE_PUBLIC, TPM_DELEGATE_OWNER_BLOB...

BUG=b:169392230, b:233949215, b:174816474
TEST=Manually check Trspi_UnloadBlob_TPM_DELEGATE_OWNER_BLOB_s works

Change-Id: Ic695d75af47652b54c40ff4815fc7c0b761957ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/trousers/+/3669929
Tested-by: Yi Chou <yich@google.com>
Reviewed-by: Andrey Pronin <apronin@chromium.org>
Commit-Queue: Yi Chou <yich@google.com>
2 files changed