R1:4bf5c452eb28

Improve error passing task IDs as URL parameter in invalid format

Summary:
Maniphest expects the values of the `ids` URL parameter to be integers. Example: http://phorge.localhost/maniphest/?ids=1,2,3,4 to show a list of tasks with those IDs.
When passing monograms instead (`T` prefix, like `T123` instead of `123`), a cryptic message `Expected a numeric scalar or null for %Ld conversion` is shown.

Thus check if `$this->taskIDs` consists of integers only; if not throw a…