Add support for ACL Conditions

[Potherca]

There have been additions to the (editors draft) of the Solid Web Access Control Specification:

• An acl:condition was added as an additional requirement for an acl:Authorization
• (Auto-)discovery for the support of such conditions (via Link headers on the ACL resource)

Adding support for ACL Conditions will (eventually) make it possible to support time-based conditions and ODRL policies.

For details see solid/web-access-control-spec#134 and the Editors Draft of the spec.

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@ylebre Is this the right place for this issue, or should it be moved elsewhere?

[melvincarvalho]

Security considerations for ACL conditions: https://github.com/webacl/secure-access-conditions/blob/main/SECURITY.md