R1:a7bd58c4bb26

Remove "AlmanacPropertyInterface" from "AlmanacNamespace"

Summary:
See <https://discourse.phabricator-community.org/t/i-cant-create-almanac-space/4424/>.

Almanac namespaces have never really had property support, but they implemented the interface in the original implementation.

At the time, this had no effect. Later changes integrated properties into the edit flows and broke this no-op integration.

Remove the interface for now. They could be given property support later, but need a bit of support code.