Allow for a few custom Checkstyle rules to be configured

[alzimmermsft]

Description

Updates a few of our custom Checkstyle rules to allow for configurations to be passed, allowing them to be more flexible in their validation.

Adds clientcore-checkstyle.xml so that all clientcore-based libraries can run Checkstyle's with configurations based on clientcore rather than azure-core.

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
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Testing Guidelines

• Pull request includes test coverage for the included changes.

[azure-sdk]

API change check

API changes are not detected in this pull request.