Unique IDs for Transformation Requests

[AndrewEckart]

Story

Currently, we have both id (autoincremented integers) and request_id (UUID) attributes on transformers. The former is used as a primary key, while the latter is not even indexed. Furthermore, we are using String as the column type although SQLAlchemy supports UUID columns for Postgres.

As a ServiceX developer I want to simplify unique IDs so I can refer to transformation requests unambiguously

Acceptance Criteria

1. The integer column is removed, and the UUID is the primary key.
2. There is a web route to view a single transformation request by its UUID
3. A new column is added, description, to be used in the web interface

Assumptions

1. Advantages to UUIDs - constant length, won't clash with other ServiceX deployments in the same namespace, already used on the frontend. Disadvantages: Ugly/long, not as nice in the web interface (alleviated by description)

[AndrewEckart]

We decided to keep both the id and the request_id. The aforementioned web route was added in #108 - it can use either identifier in the URL. In #106 and #112, the requests table was indexed on request_id to make lookups fast. A title field was added in #105.