Setup checkstyle for BigQuery extension

[dgray16]

https://maven.apache.org/plugins/maven-checkstyle-plugin/
https://github.com/spring-projects/spring-boot/blob/main/src/checkstyle/checkstyle.xml
https://github.com/spring-io/spring-javaformat

It is not an ideal solution IMHO but at least it is stable and consistent for anybody.