Query for applications that need to be provisioned.

Adds a method to the Applications domain class that can return a list of
UUIDs for applications that are ready to be provisioned. It requires
that:

- the associated portfolio and state machine have a state of COMPLETED
- the application not have been marked deleted
- the application not have an existing cloud_id
- the application does not have an existing claim on it

atst/models/application.py

@@ -1,4 +1,4 @@
-from sqlalchemy import and_, Column, ForeignKey, String, UniqueConstraint
+from sqlalchemy import and_, Column, ForeignKey, String, UniqueConstraint, TIMESTAMP
 from sqlalchemy.orm import relationship, synonym
 
 from atst.models.base import Base
@@ -40,6 +40,9 @@ class Application(
         ),
     )
 
+    cloud_id = Column(String)
+    claimed_until = Column(TIMESTAMP(timezone=True))
+
     @property
     def users(self):
         return set(role.user for role in self.members)