Document Bazel build support in the User Guide

[priyda]

Overview

I want to draw attention to the build support provided by JUnit 5 user guide. I found that Bazel build support is missing in the user guide.

It would be great if we have Bazel also. Currently covered in the documentation are Maven, Gradle, and Ant.

It would be great if we have Bazel also.

[marcphilipp]

There's currently only a sample project: https://github.com/junit-team/junit5-samples/tree/main/junit5-jupiter-starter-bazel

[marcphilipp]

I've asked @shs96c in https://github.com/bazelbuild/rules_jvm_external/pull/629#issuecomment-1195620295 if he's willing to update that so we can remove some of the boilerplate.