Add any code formatter

[RyanSkraba]

We shouldn't rely on individuals to format their code when excellent technical solutions exist!

I would prefer to use some 100% out-of-the-box configuration of a standard tool like spotless with no customized configuration, but that can be intrusive. I propose finding one that closely matches the existing format for java and xml files in this repository that makes minimal changes for now.

It doesn't need to match the format of any other connectors, but ideally it would have an .editorconfig or maven plugin to apply formatting automatically, and the build checks would fail quickly on format errors.

[Claudenw]

It looks like the original code is based on the Google style.

    <plugin>
          <groupId>com.diffplug.spotless</groupId>
          <artifactId>spotless-maven-plugin</artifactId>
          <version>2.43.0</version>
          <configuration>
            <java>
              <googleJavaFormat/>
              <removeUnusedImports></removeUnusedImports>
            </java>
            <pom>
              <sortPom></sortPom>
            </pom>
          </configuration>
     </plugin>

Might be close to what we have now.

Should we just apply the format (we can do that in the maven process-sources phase. I like this approach because it does not fail the build. On the other hand I can see that PR's might need to run mvn spotless:check to verify that the modified code was saved and pushed.

@RyanSkraba what do you think?