A report signing backend that returns a confidential-computing
attestation report obtained via configfs-tsm. Implements
io.systemd.Report.Signer.Sign(): embeds the digest as the report's
inblob and returns the outblob (plus provider and any aux/manifest
blobs). Wired up as the "tsm" mechanism with a socket-activated service.
Signed-off-by: Paul Meyer <katexochen0@gmail.com>
