Add apiUrl to allow for separation of urls. One for UI, another for API

[jonbrohauge]

Due to changes in Dependency-Track 4.0, i.e. separate URL for UI and API. This plugin needs to have to URL-inputs, one for the UI another for the API.

[sephiroth-j]

Thank you for your effort, @jonbrohauge. Unfortunately I can not accept this PR. The main reason for this, is that your change is breaking change. You re-declared the existing URL to be the one for the frontend and introduced a new URL/setting for the API that actual maters the most. This would require all users to update their Jenkins settings and/or build jobs (again after plugin version 3.0)! Another reason is that you made other unnecessary changes such as reordering of imports or reformatting javadoc in a way that is different to the existing style. In its present state, updates of the documentation and changelog would be needed as well.

A good solution would be to introduce a new optional setting for the URL to the DTrack-Frontend that, if present, would be used for the URLs to the project pages. The existing URL is still the main URL that is used for both API (primary function) and frontend, unless the new URL to the frontend is given.

[sephiroth-j]

closing in favor of own solution

[jonbrohauge]

Whatever works. As long as there is a way to define the two url's, since there clearly needs an option to allow this.