Make Classworld setup more alike to vanilla Maven (#784)

Use the plexus Launcher to start the daemon server, just like we would
launch a normal Maven process.

This improves compatibility with any extensions or plugins that assume that
their ClassLoader is a ClassRealm.

common/src/main/java/org/mvndaemon/mvnd/common/MavenDaemon.java

@@ -1,85 +0,0 @@
-/*
- * 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.
- */
-package org.mvndaemon.mvnd.common;
-
-import java.net.MalformedURLException;
-import java.net.URL;
-import java.net.URLClassLoader;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.util.stream.Stream;
-
-public class MavenDaemon {
-
-    public static void main(String[] args) throws Exception {
-        final Path mvndHome = Environment.MVND_HOME.asPath();
-        URL[] classpath = Stream.concat(
-                        /* jars */
-                        Stream.of("lib/ext", "lib", "boot")
-                                .map(mvndHome::resolve)
-                                .flatMap((Path p) -> {
-                                    try {
-                                        return Files.list(p);
-                                    } catch (java.io.IOException e) {
-                                        throw new RuntimeException("Could not list " + p, e);
-                                    }
-                                })
-                                .filter(p -> {
-                                    final String fileName = p.getFileName().toString();
-                                    return fileName.endsWith(".jar") && !fileName.startsWith("mvnd-client-");
-                                })
-                                .filter(Files::isRegularFile),
-                        /* resources */
-                        Stream.of(mvndHome.resolve("conf"), mvndHome.resolve("conf/logging")))
-                .map(Path::normalize)
-                .map(Path::toUri)
-                .map(uri -> {
-                    try {
-                        return uri.toURL();
-                    } catch (MalformedURLException e) {
-                        throw new RuntimeException(e);
-                    }
-                })
-                .toArray(URL[]::new);
-        ClassLoader loader = new URLClassLoader(classpath, null) {
-            @Override
-            protected Class<?> findClass(String name) throws ClassNotFoundException {
-                try {
-                    return super.findClass(name);
-                } catch (ClassNotFoundException e) {
-                    return MavenDaemon.class.getClassLoader().loadClass(name);
-                }
-            }
-
-            @Override
-            public URL getResource(String name) {
-                URL url = super.getResource(name);
-                if (url == null) {
-                    url = MavenDaemon.class.getClassLoader().getResource(name);
-                }
-                return url;
-            }
-        };
-        Thread.currentThread().setContextClassLoader(loader);
-        Class<?> clazz = loader.loadClass("org.mvndaemon.mvnd.daemon.Server");
-        try (AutoCloseable server = (AutoCloseable) clazz.getConstructor().newInstance()) {
-            ((Runnable) server).run();
-        }
-    }
-}