Add support for searching for Jobs by query

Add methods to JenkinsServer that support finding matching jobs:

```
public Map findJobsByTitle(String partialTitle) { ... }
public List findJobTitlesByTitle(String partialTitle) { ... }
```

Start by locating JenkinsServer and review how it currently retrieves jobs and exposes related lookup methods. Implement the two requested search methods, then verify that matching jobs are returned by title and that the title-only method returns the corresponding job titles.

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