Maven Plugin: Add default options

To use the Maven Plugin, the follow <plugin> element is required:

<plugin>
    <groupId>org.sila-standard.sila_java.library</groupId>
    <artifactId>maven_plugin</artifactId>
    <version>0.6.0</version>
    <executions>
        <execution>
            <goals>
                <goal>run</goal>
            </goals>
            <configuration>
                <features>
                    <param>${project.basedir}/src/main/resources/GreetingProvider-v1_0.sila.xml</param>
                </features>
                <grpcVersion>1.48.1</grpcVersion>
                <protobufVersion>3.19.2</protobufVersion>
            </configuration>
        </execution>
    </executions>
</plugin>

I propose to add default options so that the <executions> element is not required for typical use cases:

• run should be the default goal
• features should default to every file matching ${project.basedir}/src/main/resources/**/*.sila.xml
• grpcVersion and protobufVersion should default to the version used by this library

Afterwards, the plugin could be used like this instead:

<plugin>
    <groupId>org.sila-standard.sila_java.library</groupId>
    <artifactId>maven_plugin</artifactId>
    <version>0.6.0</version>
</plugin>