[HUDI-3130] Fixing Hive getSchema for RT tables addressing different partitions having different schemas (#4468)

* Fixing Hive getSchema for RT tables

* Addressing feedback

* temp diff

* fixing tests after spark datasource read support for metadata table is merged to master

* Adding multi-partition schema evolution tests to HoodieRealTimeRecordReader

Co-authored-by: Aditya Tiwari <aditya.tiwari@flipkart.com>
Co-authored-by: sivabalan <n.siva.b@gmail.com>

hudi-common/src/test/resources/simple-test-evolved-compatible.avsc

@@ -0,0 +1,29 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+{
+"namespace": "example.avro",
+ "type": "record",
+ "name": "User",
+ "fields": [
+     {"name": "name", "type": "string"},
+     {"name": "favorite_number",  "type": "int"},
+     {"name": "favorite_color", "type": "string"},
+     {"name": "field1", "type": ["null", "string"], "default": null},
+     {"name": "field2", "type": ["null", "string"], "default": null}
+ ]
+}