[#1005] Move checkstyle to root pom.xml

[EdgarRamirezFuentes]

Move the checkstyle plugin from integration-tests/jakarta-ee [shiro-its-jakarta-ee]/pom.xml to the root pom.xml
fixes #1005

When running the command mvn verify to make the basic checks run, it fails when it starts audit in org.apache.shiro:shiro-lang.

Audit result

Some audit errors

Build failure

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[lprimak]

Couple of comments:

• Can you please make your PR draft until it's ready?

Here is the order of preference / priority for type of checkstyle-related fixes:

• Fix the code itself to conform to checkstyle
• Use @SuppressWarnings to ignore error
• Add a line to suppressions.xml

[lprimak]

I would say for MagicNumber, @SuppressWarnings is the right thing to do

[lprimak]

Superseded by #1069