Get existing parameters of a job

### What feature do you want to see added?

We should add a method that can get us the job parameters directly without using the last build or by parsing the XML.
This will be helpful for the first build where there is no last build yet. Or if the developer does not want to get them via the XML.

### Upstream changes

No upstream changes are needed for this. We may need to add a new method that can support this functionality.

### Are you interested in contributing this feature?

Yes

Start by reviewing the existing job and build parameter APIs to identify how parameters are currently exposed. Compare the first-build case with retrieval through the last build or XML, and define done as returning job parameters without either source. No file or test is named, so repository exploration and maintainer guidance are needed.

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