[HUDI-3896] Porting Nested Schema Pruning optimization for Hudi's custom Relations (#5428)

Currently, all Hudi Relations bear performance gap relative to Spark's HadoopFsRelation 
and the reason to that is SchemaPruning optimization rule (pruning nested schemas) 
that is unfortunately predicated on usage of HadoopFsRelation, meaning that it's 
not applied in cases when any other relation is used.

This change is porting this rule to Hudi relations (MOR, Incremental, etc) 
by the virtue of leveraging HoodieSparkSessionExtensions mechanism 
injecting modified version of the original SchemaPruning rule 
that is adopted to work w/ Hudi's custom relations.

- Added customOptimizerRules to HoodieAnalysis
- Added NestedSchemaPrunning Spark's Optimizer rule
- Handle Spark's Optimizer pruned data schema (to effectively prune nested schemas)
- Enable HoodieClientTestHarness to inject HoodieSparkSessionExtensions
- Injecting Spark Session extensions for TestMORDataSource, TestCOWDataSource
- Disabled fallback to HadoopFsRelation

hudi-examples/hudi-examples-spark/src/main/java/org/apache/hudi/examples/common/HoodieExampleSparkUtils.java

@@ -33,6 +33,7 @@ public class HoodieExampleSparkUtils {
     Map<String, String> additionalConfigs = new HashMap<>();
     additionalConfigs.put("spark.serializer", "org.apache.spark.serializer.KryoSerializer");
     additionalConfigs.put("spark.kryoserializer.buffer.max", "512m");
+    additionalConfigs.put("spark.sql.extensions", "org.apache.spark.sql.hudi.HoodieSparkSessionExtension");
     return additionalConfigs;
   }