This introduces djblets.privacy, a new module designed for more easily

ensuring protection of private user data, helping Django applications to

meet GDPR compliance and to otherwise help with the management and

safe-keeping of user data.
This initial version of the module focuses on consent tracking, giving

users control over operations or processing of data. It's designed to

allow applications (and even extensions) to dynamically register things

that require consent, to check if the user granted/denied that consent,

to (later) present options for consent, and to keep an audit log for

later proof. For now, only the backend is in place, with UI helpers

coming later.
This lives almost exclusively within the djblets.privacy.consent

module (with models living in djblets.privacy.models). There are a few

components:


Consent: An enum containing values to represent whether

  consent was given or denied, or simply not set yet.


ConsentRequirement: Represents a part of a product that requires

  consent. This can be instantiated with a unique ID, displayable name

  and description, and an optional URL for learning more about the

  requirement (useful for linking to privacy policies or documentation).


ConsentRequirementsRegistry: Used to register, track, and look up

ConsentRequirement instances.


ConsentData: An object for store consent and consent-related

  information (timestamp, source of where the consent was given, and

  additional data to include), for serializing or deserializing.


BaseConsentTracker/DatabaseConsentTracker: Used to record if

  consent was given or denied for a requirement, check that consent on

  demand, and for keeping an audit log for helping to later document and

  prove when users set, denied, or revoked consent. By default,

DatabaseConsentTracker (which stores the data in the database) is

  used, but projects can make use of custom ones for storing the audit

  data in other locations outside the database.


With this module, it will be very easy to start enforcing user control

of the processing of data without a lot of additional work.
Future changes will build on this to offer standard UI for consent

management and redacting of personal information before sending to

services.

Unit tests pass.
Built the docs and checked for build and generation errors.