Enable check style for streampipes-integration-tests

[RobertIndie]

Purpose

Discussion: #815

Master issue: #820

Enable check style for streampipes-integration-tests.

This is the first try to enable checkstyle for the repo. I use the module streampipes-integration-tests as the example here.
If we are good with this PR, then we can apply it to all other modules gradually.

Approach

• Add the Indentation convention to the checkstyle.xml. I saw that we use the different Indentation convention in the repo. Here I use the google_checks.xml as the Indentation convention, which works for most of our codes.
• Change checkstyle-header to make it compatible with most of codes.
• Reformat the code in streampipes-integration-tests

Validation

1. Make sure you are at the root path of the project
2. Run maven validate -f streampipes-integration-tests

Samples

Remarks

[bossenti]

thanks a lot for taking over the initiative @RobertIndie 🙏🏼
Do we want to create an issue to track the progress with validating all modules?

[RobertIndie]

Do we want to create an issue to track the progress with validating all modules?

Great idea. I have created an issue to track it: #820