Consolidate duplicate configurations

Maintain a single source of truth for configuration files instead of duplicating them across the codebase. Duplicated configurations (like banned-signatures.txt files) lead to maintenance challenges, potential inconsistencies, and confusion about which version is authoritative.

For shared configuration rules like import bans or code quality checks:

• Create a common configuration file (e.g., banned-signatures-common.txt)
• Reference this common file from different modules when needed
• Document the location of the common file

Example: Instead of having multiple copies:

// In module1/banned-signatures.txt
@defaultMessage Don't use Maven classes. They won't be available when using Gradle.
org.apache.maven.**

// In module2/banned-signatures.txt
@defaultMessage Don't use Maven classes. They won't be available when using Gradle.
org.apache.maven.**

Consolidate into a common file:

// In common/banned-signatures-common.txt
@defaultMessage Don't use Maven classes. They won't be available when using Gradle.
org.apache.maven.**

This approach ensures that when configuration rules need to be updated, the change happens in a single place, maintaining consistency across the codebase.