add functionality required for this test load_collection & collect

add functionality required for this test load_collection & collect

https://github.com/apache/incubator-wayang/blob/1e0f9e8166225176fe3022de5fbcce3dbcba96b9/python/src/pywy/tests/train_logistic_test.py#L24

```python

# limitations under the License.
#

import pytest

from pywy.dataquanta import WayangContext
from pywy.platforms.java import JavaPlugin
from pywy.platforms.spark import SparkPlugin

# TODO: add functionality required for this test load_collection & collect
@pytest.mark.skip(reason="no way of currently testing this, since we are missing implementations for load_collection & collect")
def test_train_and_predict():
ctx = WayangContext().register({JavaPlugin, SparkPlugin})

features = ctx.load_collection([[0.0, 1.0], [1.0, 0.0], [1.0, 1.0], [0.0, 0.0]])
labels = ctx.load_collection([1.0, 1.0, 0.0, 0.0])

model = features.train_logistic_regression(labels)
predictions = model.predict(features)

result = predictions.collect()
print("Predictions:", result)

assert len(result) is 4, f"Expected len(result) to be 4, but got: {len(result)}"
for pred in result:
assert pred in [0.0, 1.0], f"Expected prediction to be in [0.0, 0.1], but got: {pred}"

```

f35294bf9a27cc63281f965c1bf55a42419e4b35

Start with python/src/pywy/tests/train_logistic_test.py at the skipped test_train_and_predict test and review the referenced load_collection and collect calls. Trace the existing WayangContext, JavaPlugin, and SparkPlugin implementations to determine the missing functionality. Done means the test can run without its skip marker and its collection and prediction assertions pass.

Written by the indexing model from the issue text.