Enable the use of external identifiers for concepts referenced from competencies

[siuc-nate]

In the context of the spreadsheet-based bulk upload:

We want to enable users to upload Concept Schemes/Concepts with simple, human-friendly IDs like 1 or 1A.

We also want to those users to be able to reference those Concepts from their Competencies using those same identifiers.

This will likely require some form of composite identifier along the lines of:
[organization ID]/[type]/[id for that type as provided by the user]/[other type as provided by the user?]/[other id as provided by the user?]

For example, a Competency Framework:
abc123pubkeyforanorganization/competencyframework/1
And for Competencies from that Framework:
abc123pubkeyforanorganization/competencyframework/1/competency/1
abc123pubkeyforanorganization/competencyframework/1/competency/2
abc123pubkeyforanorganization/competencyframework/1/competency/3

From the user's perspective, they would then be able to put something like "1-3" in the spreadsheet to reference framework 1, competency 3 (for that organization).

The same approach should work for Concept Schemes/Concepts:
abc123pubkeyforanorganization/conceptscheme/1
abc123pubkeyforanorganization/conceptscheme/1/concept/1
abc123pubkeyforanorganization/conceptscheme/1/concept/2
abc123pubkeyforanorganization/conceptscheme/1/concept/3

Whether or not those identifiers ultimately get encoded to something else like a UUID hopefully shouldn't make a difference as far as the user is concerned. However, it's probably not wise to generate a CTID based on such a UUID in case the user decides (intentionally or not) to reuse a particular numeric ID combination for some other competency/framework later on, not knowing that that would break the generated UUID-based relationships.