Add support for Azure CDN endpoint URL

[Minreaux]

Resolves #84

Description

These changes add support for an Azure CDN endpoint URL into the Azure Artifact Manager plugin, which will pull the Azure CDN endpoint URL from the configured Azure Storage Account, if and only if the Azure CDN endpoint URL is configured, and then distribute artifacts in Jenkins using the Azure CDN URL instead of the Azure Storage Account blob URL.

Otherwise, it will use the Azure Storage Account blob URL like normal. This PR is dependent on the upstream changes for the Azure Storage plugin here: https://github.com/jenkinsci/azure-storage-plugin/pull/280

I also fixed some issues I discovered while working on this so that I could get the plugin building locally without issue and to ensure that the Azure Storage and Azure Artifact Manager plugins had the same Jenkins version as a minimum dependency:

• Updated Jenkins version and bom to 2.387
• Fixed some warnings with the pom.xml

Testing done

This change was tested locally in VSCode configured for Java/Jenkins development. I updated the JUnit tests to account for this new feature. I tested this locally using the mvn verify command.

Since these changes are dependent on the upstream changes I've made to the Azure Storage plugin, I tested these changes in a local instance of Jenkins using the mvn hpi:run command using a local version of the Azure Storage plugin containing the changes from this PR: https://github.com/jenkinsci/azure-storage-plugin/pull/280.

### Submitter checklist
- [x] Make sure you are opening from a **topic/feature/bugfix branch** (right side) and not your main branch!
- [x] Ensure that the pull request title represents the desired changelog entry
- [x] Please describe what you did
- [x] Link to relevant issues in GitHub or Jira
- [x] Link to relevant pull requests, esp. upstream and downstream changes
- [x] Ensure you have provided tests - that demonstrates feature works or fixes the issue

[Minreaux]

This is blocked until https://github.com/jenkinsci/azure-storage-plugin/pull/280 is submitted; will need to update Azure Storage plugin version dependency in this PR once that PR is submitted.

[Minreaux]

Tagging maintainer for review @timja.

[Minreaux]

Thanks for all your help!