add dataset/project search by user/organization identifier

[sfmcintyre]

• use users/:userReference/datasets + organizations/:organizationReference/datasets list endpoints to find list of available datasets
• do we have a users/:userReference/projects endpoint? perhaps implement?
• should we have a organizations/:organizationReference/projects endpoint? pulling linked projects with data from org?
• implement dataset/project menu as dropdown (with two types of entity)

[sfmcintyre]

(building off of #12) should use redivis-js to access these entities, ideally migrate whole app to use exclusively client library & remove API helpers