R1:1fb2f39fc0f6

Enable prefilling of projects and priority fields in Maniphest task creation

Summary:
Projects and priority inputs can be prefilled similar to how title
and description fields work.

Prefilling of projects already worked but used PHIDs instead of
more user friendly name so I changed that too.

Test Plan:
Visit [[/maniphest/task/create/?projects=Maniphest;Easy&priority=100&assign=vrana&title=Hip-hip&description=hooray!|example]]
and see prefilled form fields.

Reviewers: epriestley, #blessed_reviewers…