Use more fields when filtering in contributors query

[ja573]

At present search is done in fullName and orcid. We should include lastName, too. A use case is searching a contributor without their middle name doesn't return the expected contributor, e.g. filtering with "Martin Eve" doesn't return "Martin Paul Eve"s record.

[rhigman]

Filtering on lastName alone wouldn't solve the problem stated in the use case (as searching for "Martin Eve" in the lastName field wouldn't return "Eve"). We would also need to split the filter string on spaces, and search for each substring separately. For the use case given, searching in fullName would then return the desired result, without needing to include lastName.

[rhigman]

I attempted splitting the filter string on spaces in d28fef6, but the results returned were poor, as the number of hits potentially increased every time a new word/name was added to the filter string - making it harder to see actual matches.