Add Project search functionality

[camallen]

Allow folks to search for projects via the API project's search functionality, E.g. by display name and/or tags

# by display_name (default)
curl -H "Accept: application/vnd.api+json; version=1" -H "Content-Type: application/json" 'https://www.zooniverse.org/api/projects?search=scribes&cards=true&launch_approved=true'
# by tags
curl -H "Accept: application/vnd.api+json; version=1" -H "Content-Type: application/json" 'https://www.zooniverse.org/api/projects?search=tag:egypt&cards=true&launch_approved=true'

Inspired by / more details at https://www.zooniverse.org/talk/17/1656701?comment=2694491