[SPARK-50812][ML][PYTHON][CONNECT] Support TargetEncoderModel on Connect

### What changes were proposed in this pull request?
Support TargetEncoderModel on Connect

### Why are the changes needed?
feature parity

### Does this PR introduce _any_ user-facing change?
yes

### How was this patch tested?
enabled parity tests

### Was this patch authored or co-authored using generative AI tooling?
no

Closes #49648 from zhengruifeng/ml_connect_te.

Authored-by: Ruifeng Zheng <[email protected]>
Signed-off-by: Ruifeng Zheng <[email protected]>

Author: zhengruifeng

mllib/src/main/resources/META-INF/services/org.apache.spark.ml.Estimator

@@ -60,4 +60,4 @@ org.apache.spark.ml.feature.PCA
 org.apache.spark.ml.feature.Word2Vec
 org.apache.spark.ml.feature.CountVectorizer
 org.apache.spark.ml.feature.OneHotEncoder
-
+org.apache.spark.ml.feature.TargetEncoder

mllib/src/main/resources/META-INF/services/org.apache.spark.ml.Transformer

@@ -65,4 +65,4 @@ org.apache.spark.ml.feature.PCAModel
 org.apache.spark.ml.feature.Word2VecModel
 org.apache.spark.ml.feature.CountVectorizerModel
 org.apache.spark.ml.feature.OneHotEncoderModel
-
+org.apache.spark.ml.feature.TargetEncoderModel

mllib/src/main/scala/org/apache/spark/ml/feature/TargetEncoder.scala

@@ -286,6 +286,8 @@ class TargetEncoderModel private[ml] (
     @Since("4.0.0") private[ml] val stats: Array[Map[Double, (Double, Double)]])
   extends Model[TargetEncoderModel] with TargetEncoderBase with MLWritable {
 
+  private[ml] def this() = this(Identifiable.randomUID("TargetEncoder"), Array.empty)
+
   /** @group setParam */
   @Since("4.0.0")
   def setInputCol(value: String): this.type = set(inputCol, value)

python/pyspark/ml/tests/connect/test_parity_feature.py

@@ -58,14 +58,6 @@ def test_string_indexer_handle_invalid(self):
     def test_string_indexer_from_labels(self):
         super().test_string_indexer_from_labels()
 
-    @unittest.skip("Need to support.")
-    def test_target_encoder_binary(self):
-        super().test_target_encoder_binary()
-
-    @unittest.skip("Need to support.")
-    def test_target_encoder_continuous(self):
-        super().test_target_encoder_continuous()
-
     @unittest.skip("Need to support.")
     def test_vector_size_hint(self):
         super().test_vector_size_hint()