Allow configuring credentials for custom Gradle plugin repository

[alextu]

Allow configuring credentials for custom Gradle plugin repository.

Testing done

Mainly manual testing with a custom Artifactory:

• No credentials and custom public repository
• No credentials and custom private repository
• Wrong credentials and custom private repository
• Good credentials and custom private repository

Submitter checklist

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1. Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
2. Ensure that the pull request title represents the desired changelog entry
3. Please describe what you did
4. Ensure you have provided tests - that demonstrates feature works or fixes the issue