Narrowly fix web UI fatal for "almanac.service.edit" Conduit API method

Summary:
See T13120. See T12414. See PHI145. See PHI473. Almanac services require a type before they can do anything, and EditEngine currently builds one with no type. We then fatal when trying to do mundane things like generate documentation.

Instead, build a generic but complete Service for documentation generation in the web UI. This is similar to the previous Drydock Blueprint change from D18849 (or some earlier diff in that series).

(You still probably can't use this method to create a service; I'll fix that in the next change.)

Test Plan:

• Viewed "almanac.service.edit" in the web UI.
  • Before: immediate fatal ("No Almanac service type "" exists!").
  • After: Page works. No claims about the method doing anything useful.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D19315