maven.compiler.release support is not consistent with javac

[slandelle]

We want scala-maven-plugin's support of maven.compiler.release to be consistent with maven-compiler plugin's.

On the Java side, maven.compiler.release translates to --release that was introduced in Java 9.
Trying to use it with Java 8 triggers a invalid flag: --release crash.
As of scala-maven-plugin 3.8.1, compilation succeeds.

We should crash as well.