### What changes were proposed in this pull request?
This PR adjusts `_to_java` and `_from_java` of `OneVsRest` and `OneVsRestModel` to preserve `weightCol`.
### Why are the changes needed?
Currently both `Params` don't preserve `weightCol` `Params` when data is saved / loaded:
```python
from pyspark.ml.classification import LogisticRegression, OneVsRest, OneVsRestModel
from pyspark.ml.linalg import DenseVector
df = spark.createDataFrame([(0, 1, DenseVector([1.0, 0.0])), (0, 1, DenseVector([1.0, 0.0]))], ("label", "w", "features"))
ovr = OneVsRest(classifier=LogisticRegression()).setWeightCol("w")
ovrm = ovr.fit(df)
ovr.getWeightCol()
## 'w'
ovrm.getWeightCol()
## 'w'
ovr.write().overwrite().save("/tmp/ovr")
ovr_ = OneVsRest.load("/tmp/ovr")
ovr_.getWeightCol()
## KeyError
## ...
## KeyError: Param(parent='OneVsRest_5145d56b6bd1', name='weightCol', doc='weight column name. ...)
ovrm.write().overwrite().save("/tmp/ovrm")
ovrm_ = OneVsRestModel.load("/tmp/ovrm")
ovrm_ .getWeightCol()
## KeyError
## ...
## KeyError: Param(parent='OneVsRestModel_598c6d900fad', name='weightCol', doc='weight column name ...
```
### Does this PR introduce any user-facing change?
After this PR is merged, loaded objects will have `weightCol` `Param` set.
### How was this patch tested?
- Manual testing.
- Extension of existing persistence tests.
Closes#27190 from zero323/SPARK-30504.
Authored-by: zero323 <mszymkiewicz@gmail.com>
Signed-off-by: Sean Owen <srowen@gmail.com>
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