Package the license and repo with the plugin

We cannot use this plugin internally because one of our tool flags it because the license is not packaged with the plugin.

For example check Dexcount Gradle Plugin. The license is properly packaged in the POM:

<licenses>
    <license>
        <name>The Apache Software License, Version 2.0</name>
        <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
        <distribution>repo</distribution>
    </license>
</licenses>

There is no license in the modules-graph-assert latest POM.

Similarly, the source repo should also be included. Again, for the dexcount-gradle-plugin it's:

<scm>
    <connection>scm:git:git://github.com/KeepSafe/dexcount-gradle-plugin.git</connection>
    <developerConnection>scm:git:ssh://git@github.com/KeepSafe/dexcount-gradle-plugin.git</developerConnection>
    <url>https://github.com/KeepSafe/dexcount-gradle-plugin/</url>
</scm>

I think by just adding vacUrl in the gradlePlugin, the license and the repo URL will be picked up automatically. See https://github.com/KeepSafe/dexcount-gradle-plugin/blob/d17e9cf40fdb6bd8f9740f2900443a660ce932a7/build.gradle#L269C1-L269C13

Start in the Gradle plugin publication configuration, at the gradlePlugin declaration mentioned in the issue, and inspect the generated POM for the published plugin. Compare it with the linked Dexcount POM; done means the published metadata includes the license and source repository URLs.