Rework dataset load method and apply filtering

Why these changes are needed:
* Updating the load method to support partition prefixes enables
PyArrow to only load data from partitions matching the prefix and
avoid scanning the entire TIMDEXDataset.dataset. The added filtering
method will be used in future read operations to retrieve relevant
rows from TIMDEXDataset.dataset.

How this addresses that need:
* Create TIMDEX_DATASET_FILTER_COLUMNS global variable
* Add '_get_filtered_dataset' method
* Add private helper method '_get_partition_prefixes'
* Add private helper method '_parse_date_filters'
* Update load method to support partition prefixes and filter method
* Add and update unit tests for load and filter methods

Side effects of this change:
* TIMDEXDataset.load no longer returns self and instead assigns
pyarrow.dataset.Dataset to self.dataset.

Relevant ticket(s):
* https://mitlibraries.atlassian.net/browse/TIMX-425

Author: jonavellecuerdo

Pipfile.lock

@@ -23,22 +23,34 @@ def _test_env(monkeypatch):
 
 @pytest.fixture
 def local_dataset_location(tmp_path):
-    return str(tmp_path / "tests/fixtures/local_datasets/dataset")
+    return str(tmp_path / "local_dataset/")
 
 
 @pytest.fixture
 def local_dataset(local_dataset_location):
     timdex_dataset = TIMDEXDataset(local_dataset_location)
-    records = generate_sample_records_with_simulated_partitions(num_records=5_000)
-    timdex_dataset.write(records)
+    timdex_dataset.write(
+        generate_sample_records_with_simulated_partitions(num_records=5_000)
+    )
     timdex_dataset.load()
     return timdex_dataset
 
 
 @pytest.fixture
 def new_local_dataset(tmp_path) -> TIMDEXDataset:
-    location = str(tmp_path / "new_local_dataset")
-    return TIMDEXDataset(location=location)
+    return TIMDEXDataset(location=str(tmp_path / "new_local_dataset/"))
+
+
+@pytest.fixture
+def fixed_local_dataset(tmp_path) -> TIMDEXDataset:
+    """Local dataset with a fixed set of configurations.
+
+    This fixture is required to perform unit tests for TIMDEXDataset.filter
+    method.
+    """
+    timdex_dataset = TIMDEXDataset(str(tmp_path / "fixed_local_dataset/"))
+    timdex_dataset.write(generate_sample_records(num_records=5_000, run_id="abc123"))
+    return timdex_dataset
 
 
 @pytest.fixture