Store Almanac "service types" instead of "service classes"

Summary:
Ref T10449. Currently, we store classes (like "AlmanacClusterRepositoryServiceType") in the database.

Instead, store types (like "cluster.repository").

This is a small change, but types are a little more flexible (they let us freely reanme classes), a little cleaner (fewer magic strings in the codebase), and a little better for API usage (they're more human readable).

Make this minor usability change now, before we unprototype.

Also make services searchable by type.

Also remove old Almanac API endpoints.

Test Plan:

• Ran migration, verified all data migrated properly.
• Created, edited, rebound, and changed properties of services.
• Searched for services by service type.
• Reviewed available Conduit methods.

Reviewers: chad

Reviewed By: chad

Subscribers: yelirekim

Maniphest Tasks: T10449

Differential Revision: https://secure.phabricator.com/D15346