Replace TableSpec internals with pvc.HiveDataset

Summary:
1. Replace namespace, table and ds in TableSpec with pvc.HiveDataset
2. Whenever TableSpec is initialized, we initialize a HiveDataset and pass it in so that it's possible to designate multiple partitions.
3. For pvc queries, use table_spec.dataset directly for most of the time.
4. Update all related interfaces to comply with this change.

It turns out TableSpec is defined as a very low level data structure and referenced by many files (>30)... I tried my best to update all of them via code search, unit test and integration test. But to be honest I don't have any context about this rl project at all except knowing this is a fblearner flow pipeline. So please let me know if I miss anything. Thanks!

Reviewed By: kittipatv

Differential Revision: D25538742

fbshipit-source-id: 5df4d36e60d5717c3042a9728daafa86e080a9da

reagent/test/workflow/test_preprocessing.py

@@ -5,6 +5,7 @@ import logging
 import unittest
 
 import numpy as np
+import pvc
 import pytest
 from reagent.preprocessing.identify_types import CONTINUOUS
 
@@ -48,7 +49,7 @@ class TestPreprocessing(ReagentSQLTestBase):
         num_samples = NUM_ROWS // 2
         preprocessing_options = PreprocessingOptions(num_samples=num_samples)
 
-        table_spec = TableSpec(table_name=TABLE_NAME)
+        table_spec = TableSpec(dataset=pvc.HiveDataset(table=TABLE_NAME))
 
         normalization_params = identify_normalization_parameters(
             table_spec, COL_NAME, preprocessing_options, seed=self.test_class_seed

reagent/test/workflow/test_query_data.py

@@ -5,6 +5,7 @@ import logging
 import unittest
 
 import numpy as np
+import pvc
 import pytest
 
 # pyre-fixme[21]: Could not find `pyspark`.
@@ -49,7 +50,7 @@ class TestQueryData(ReagentSQLTestBase):
     def _discrete_read_data(
         self, custom_reward_expression=None, gamma=None, multi_steps=None
     ):
-        ts = TableSpec(table_name=self.table_name)
+        ts = TableSpec(dataset=pvc.HiveDataset(table=self.table_name))
         dataset: Dataset = query_data(
             input_table_spec=ts,
             discrete_action=True,

reagent/test/workflow/test_query_data_parametric.py

@@ -5,6 +5,7 @@ import logging
 import unittest
 
 import numpy as np
+import pvc
 import pytest
 
 # pyre-fixme[21]: Could not find `pyspark`.
@@ -49,7 +50,7 @@ class TestQueryDataParametric(ReagentSQLTestBase):
     def _parametric_read_data(
         self, custom_reward_expression=None, gamma=None, multi_steps=None
     ):
-        ts = TableSpec(table_name=self.table_name)
+        ts = TableSpec(dataset=pvc.HiveDataset(table=self.table_name))
         dataset: Dataset = query_data(
             input_table_spec=ts,
             discrete_action=False,