Improve error messages for MojoExecutionException

By default Maven does not log any cause for MojoExecutionException. That may lead to the following output:

Error(s) found in manifest configuration (org.apache.felix:maven-bundle-plugin:5.1.7:manifest:scr-metadata:process-classes)

Only with -debug the cause is also emitted.
This should be improved by also logging the message of the cause in https://github.com/apache/felix-dev/blob/28b4c77883b8dbdea06e723dc4e5a3eba7393f34/tools/maven-bundle-plugin/src/main/java/org/apache/felix/bundleplugin/ManifestPlugin.java#L132-L167