Add informed consent input data type

[Whathecode]

We require informed consent as a new input data types that could be implemented in core, the specifications are copied from here: https://github.com/cph-cachet/carp.sensing-flutter/blob/develop-1.1.0/carp_core/lib/common/application/input_data.dart

Informed consent

 /// The time this informed consent was signed.
 DateTime signedTimestamp;

 /// The location where this informed consent was signed.
 String? signedLocation;

 /// The ID of the participant who signed this consent.
 String? userID;

 /// The full name of the participant who signed this consent.
 String name;

 /// The content of the signed consent.
 ///
 /// This may be plain text or JSON.
 String? consent;

 /// The image of the provided signature in png format as bytes.
 String? signatureImage;

[Whathecode]

I'm very hesitant to consider informed consent "simply" an input type. The original idea was to make this much more part of the core framework, e.g., prevent data collection from happening before any consent has been given.

Consent should be much more integrated into the deployment workflow, rather than an input type extension point. Probably, a separate endpoint on deployments.

[bardram]

We have decided to add the IC as part of the study protocol. This will then be downloaded as part of the deployment for a participant.

We have also decided to upload the IC as participant data with a specific input type. This is much more simple and can be done with the existing CARP Core implementation. In addition, we would not need to change the database structure in a running deployment.

If someone has the time and skills to implement a full-blown informed consent model i CARP Core, we will migrate to this later.