Implement Unit of Measure (UoM) ADR

[cloudxxx8]

🚀 Feature Request

Relevant Package [REQUIRED]

This feature request is for core-metadata

Description [REQUIRED]

Implement the design in the ADR
https://docs.edgexfoundry.org/2.2/design/adr/core/0022-UoM/
GET /api/v2/uom
In addition, I suggest to add a GET API to retrieve the current UoM settings. It will just load the UoMFile and return the content.
Also, use the Accept header to determine whether the API should return JSON or TOML format.
Ref: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept

Furthermore, the Values of UoM should be String array
Values=["lbs", "ounces", "kilos", "grams"]
not
Values="lbs,ounces,kilos,grams"

[JamesKButcher]

Moving to icebox because not happening for Kamakura

[cloudxxx8]

move to release backlog for levski

[cloudxxx8]

@hahattan in the Core working group today, we decided to implement the GET API for this issue