Remove sink desc

[Yicong-Huang]

This PR refactors the handling of sink operators in Texera by removing the sink descriptor and introducing a streamlined approach to creating physical sink operators during compilation and scheduling. Additionally, it shifts the storage assignment logic from the logical layer to the physical layer.

1. Sink Descriptor Removal: Removed the sink descriptor, physical sink operators are no longer created through descriptors. In the future, we will remove physical sink operators.
2. Sink Operator Creation:

• Introduced a temporary factory for creating physical sink operators without relying on a descriptor.
• Physical sink operators are now considered part of the sub-plan of their upstream logical operator. For example: If the HashJoin logical operator requires a sink, its physical sub-plan includes the building physicalOp, probing physicalOp, and the sink physicalOp.

3. Storage Assignment Refactor:

• Merged the storage assignment logic into the physical layer, removing it from the logical layer.
• When a physical sink operator is created (either during compilation or scheduling), its associated storage is also created at the same moment.

[shengquan-ni]

LGTM with minor comments.