Gradle: Add DCL support

[hfhbd]

What are you trying to accomplish?

Gradle will create a new Declarative DSL (.dcl), a strict subset of the existing Kotlin DSL (.kts) focussing on declarative usage.

Dependabot implementation is the same, because Gradle won't change dependency management, but uses .dcl file suffix.

So every file pattern matcher needs to be updated to also use .dcl. BTW any reason to not use a global definition of build and settings files instead of repeating define them in every ruby file over and over?

Anything you want to highlight for special attention from reviewers?

Your test setup is quite complex, do we also need a new test-fixture repo: https://github.com/orgs/dependabot-fixtures/repositories?

How will you know you've accomplished your goal?

Use a settings.gradle.dcl and a build.gradle.dcl file, like I did in https://github.com/hfhbd/mavencentral/actions/runs/16872774437/job/47790546819

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.