R1:d56a37b63673

Allow Almanac Bindings to be enabled/disabled via API and support the "properties" attachment

Summary:
Depends on D19340. Ref T12414. Ref T13120. See T12414 for some discussion about direction here.

Since I think retaining "enabled/disabled" as a simple flag is reasonable, expose it via the API for readers and writers.

Also expose binding properties.

Test Plan:
- Searched for bindings and properties with "alamanc.binding.search".
- Enabled and disabled bindings with "almanac.binding.edit".