Physical Flows: auto assign an external id and ensure these are searchable / addressable

[davidwatkins73]

Description

Something like WPF-1234. Possibly something similar for Physical specs WPS-4321. Adding ddl label as we will probably need a default value on the table.

Users should be able to search for these identifiers and we also need to ensure that they can be used in urls to open the flows/specs directly from other tools.

Requested by AP.

Resourcing

We intend to contribute this feature