cryptsetup: measure via the pcrextend varlink service

cryptsetup: measure via the pcrextend varlink service

Measure the volume key and unlock keyslot through io.systemd.PCRExtend
instead of driving the TPM directly via tpm2-util, matching how the
verity and imds measurements already work.

Bank selection and the TPM context now live entirely in
systemd-pcrextend. As a result the tpm2-measure-bank= crypttab option
can no longer be honored per volume and is now a deprecated no-op.

Signed-off-by: Paul Meyer <katexochen0@gmail.com>