Summary:
`./bin/lipsum` allows to fill up a Phorge instance with bogus data for testing. When creating a project, the code creates a project title, project status, random subscribers/members and picks a random project creator, but does not set a project description.

Make this code also set a project description (which is implemented as a custom field).

Closes T15748

Test Plan:
* On the CLI, use `./bin/lipsum generate projects` to create a bogus project.
* In the web browser, go to `/project/query/all/` and open the project page of the recently created bogus project: See no project description.
* Apply this change.
* On the CLI, use `./bin/lipsum generate projects` to create another bogus project.
* In the web browser, go to `/project/query/all/` and open the project page of the recently created bogus project: See a random project description.

Reviewers: O1 Blessed Committers, 20after4

Reviewed By: O1 Blessed Committers, 20after4

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15748

Differential Revision: https://we.phorge.it/D25545