Attach signature on annotation

Attach signature from interview to previously uploaded PDF contracts at all places annotated with text from request,
with desired height on pdf. Annotations must contain text with either preselected values, or alternative can be supplied.
If user wishes to use signature supplied during onboarding, DEFAULT signature type should be used.

Preselected values are: DEFAULT, INITIALS, PATIENTS_SIGNATURE, NON_MEDICAL_SIGNATURE_1, NON_MEDICAL_SIGNATURE_2,
MEDICAL_SIGNATURE_1, MEDICAL_SIGNATURE_2

Endpoint is intended to be used as fluent api. One call to the api gives in responses id of the signed document which
can then be used in the subsequent call to continuously add another signature on a different annotation.