Maven Wrapper support

[ascopes]

Is there an existing issue for this?

• [x] I have searched the existing issues (and cannot find one under this wording, so hopefully I have not duplicated anything)

Feature description

I would like dependabot to check the primary Maven repository for the latest version of org.apache.maven:maven-core to determine the newest version of Maven.

If a .mvn/wrapper directory exists, dependabot should run ./mvnw --version to see which version of Maven is configured via the Maven wrapper.

in the case of a discrepency, ./mvnw wrapper:wrapper -Dmaven=${version} should be run to update the Maven wrapper version.

[yeikel]

Duplicate of #485