Sum and show time saved from running recipes, similar to Gradle plugin

[timtebeek]

What problem are you trying to solve?

Show folks how much time is estimated to be saved through running recipes, to show appreciation to recipe authors and encourage more use.

Describe the solution you'd like

The same as was done for the Gradle plugin, but now applied to the Maven plugin

• https://github.com/openrewrite/rewrite-gradle-plugin/pull/294

[nicolasb29]

I have created a pull request #782. Can you check because I never use Maven.