[KYUUBI-SHADED #49] Create relocated package for spark-connect-rpc

### _Why are the changes needed?_

This PR introduces a new module `kyuubi-relocated-spark-connect-rpc`, which forks [Spark Connect proto files](https://github.com/apache/spark/tree/5b2d2149b615acdd8730547a1f24c2b637222545/sql/connect/common/src/main/protobuf) and shifts the package name from `org.apache.spark.connect.proto` to `org.apache.kyuubi.shaded.spark.connect.proto`, this is a precondition for Kyuubi to support Spark Connect

### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible

- [ ] Add screenshots for manual tests if appropriate

- [ ] [Run test](https://kyuubi.readthedocs.io/en/master/develop_tools/testing.html#running-tests) locally before make a pull request

Closes #49 from pan3793/spark-connect-rpc.

316d46f [Cheng Pan] fi
914e1ba [Cheng Pan] Add kyuubi-relocated-spark-connect-rpc

Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: Cheng Pan <chengpan@apache.org>

kyuubi-relocated-spark-connect-rpc/pom.xml

@@ -0,0 +1,110 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+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.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.apache.kyuubi</groupId>
+        <artifactId>kyuubi-relocated-parent</artifactId>
+        <version>0.5.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>kyuubi-relocated-spark-connect-rpc</artifactId>
+    <description>Relocated Spark Connect RPC classes used by Kyuubi internally.</description>
+
+    <properties>
+        <grpc.version>1.65.1</grpc.version>
+        <protobuf.version>3.25.1</protobuf.version>
+    </properties>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>io.grpc</groupId>
+                <artifactId>grpc-bom</artifactId>
+                <version>${grpc.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+            <dependency>
+                <groupId>com.google.protobuf</groupId>
+                <artifactId>protobuf-bom</artifactId>
+                <version>${protobuf.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-protobuf</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-stub</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.protobuf</groupId>
+            <artifactId>protobuf-java</artifactId>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- Add protobuf-maven-plugin and provide ScalaPB as a code generation plugin -->
+            <plugin>
+                <groupId>org.xolstice.maven.plugins</groupId>
+                <artifactId>protobuf-maven-plugin</artifactId>
+                <version>0.6.1</version>
+                <configuration>
+                    <protocArtifact>com.google.protobuf:protoc:${protobuf.version}:exe:${os.detected.classifier}</protocArtifact>
+                    <pluginId>grpc-java</pluginId>
+                    <pluginArtifact>io.grpc:protoc-gen-grpc-java:${grpc.version}:exe:${os.detected.classifier}</pluginArtifact>
+                    <protoSourceRoot>src/main/protobuf</protoSourceRoot>
+                </configuration>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>compile</goal>
+                            <goal>compile-custom</goal>
+                            <goal>test-compile</goal>
+                        </goals>
+                        <configuration>
+                            <pluginParameter>@generated=omit</pluginParameter>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <!-- Used to resolve variables in the 'version' tag -->
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>flatten-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

kyuubi-relocated-spark-connect-rpc/src/main/protobuf/README.md

@@ -0,0 +1,8 @@
+proto files are copied from
+https://github.com/apache/spark/tree/5b2d2149b615acdd8730547a1f24c2b637222545/sql/connect/common/src/main/protobuf
+
+and with one additional change in each proto file
+```patch
+- option java_package = "org.apache.spark.connect.proto"
++ option java_package = "org.apache.kyuubi.shaded.spark.connect.proto"
+```