Refactor czi_hosted and server into backend directory, pull common code into backend/common, refactor tests (#2102)

* move local_server -> backend/server server-> backend/czi_hosted, pull common code into backend/common update imports, tests and make commands

backend/czi_hosted/db/cellxgene_orm.py

@@ -0,0 +1,58 @@
+import uuid
+
+from sqlalchemy import Column, DateTime, ForeignKey, String, func, JSON
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import relationship
+
+Base = declarative_base()
+
+
+class CellxGeneUser(Base):
+    """
+    A registered CellxGene user.
+    Links a user to their annotations
+    """
+
+    __tablename__ = "cxguser"
+
+    id = Column(String, primary_key=True)
+    created_at = Column(DateTime, nullable=False, server_default=func.now())
+    updated_at = Column(DateTime, nullable=False, server_default=func.now(), onupdate=func.now())
+
+    # Relationships
+    annotations = relationship("Annotation", back_populates="cxguser")
+
+
+class Annotation(Base):
+    """
+    An annotation is a link between a user, a dataset and tiledb dataframe. A user can have multiple annotations for a
+    dataset, the most recent annotation (based on created_at) will be the default returned when queried
+    """
+
+    __tablename__ = "annotation"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4, unique=True, nullable=False)
+    tiledb_uri = Column(String)
+    user_id = Column(String, ForeignKey("cxguser.id"), nullable=False)
+    dataset_id = Column(UUID, ForeignKey("cxgdataset.id"), nullable=False)
+
+    created_at = Column(DateTime, nullable=False, server_default=func.now())
+    schema_hints = Column(JSON)
+    # Relationships
+    cxguser = relationship("CellxGeneUser", back_populates="annotations")
+    dataset = relationship("CellxGeneDataset", back_populates="annotations")
+
+
+class CellxGeneDataset(Base):
+    """
+    Datasets refer to datasets stored by cellxgene
+    """
+
+    __tablename__ = "cxgdataset"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4, unique=True, nullable=False)
+    name = Column(String, unique=True, index=True)
+
+    created_at = Column(DateTime, nullable=False, server_default=func.now())
+    annotations = relationship("Annotation", back_populates="dataset")