Merge pull request #3213 from matrix-org/rav/consent_handler

docs/privacy_policy_templates/README.md

docs/privacy_policy_templates/en/1.0.html

docs/privacy_policy_templates/en/success.html

synapse/app/homeserver.py

synapse/config/__init__.py

synapse/config/consent_config.py

synapse/config/homeserver.py

synapse/config/key.py

synapse/http/server.py

synapse/rest/consent/__init__.py

synapse/rest/consent/consent_resource.py

synapse/server.py

synapse/storage/registration.py

synapse/storage/schema/delta/48/add_user_consent.sql