search candidate for job order pipeline shall be improved

[skrchnavy]

Steps to reproduce

• Select 'Job Orders' menu
• Open a job order with candidate(s) in pipeline
• open 'add candidate ...' action
• press 'Search by full name' Result
• all candidates are displayed, no good visual indication that candidate is in pipeline

Proposed change (not sure which is best)

• not to display candidates already in pipeline
• to use better visual indication of candidate in pipeline
• to split list: not added candidates / already added candidates