Adding a curie type

[cmungall]

approved on linkml develper call 2023-02-03

@hsolbrig - this is the initial commit on types.yaml: https://github.com/linkml/linkml-model/blob/f9d1fa4ce407189e3a27eafbad53fbf52a2487e6/linkml_model/model/schema/types.yaml

[hsolbrig]

Before we integrate this, I think we need to define the behavior of this type.

Questions:

1. is ":x" a valid Curie? how about "x" w/o the colon.
2. is "ex:x" a valid Curie if "ex" is not in a prefix map?
3. I'm assuming that "https://ex.org/x" is NOT a valid curie -- is there a RE or formal spec that we should use to validate tthese

[cmungall]

Added a conforms_to to the W3C spec.

Note we already have an implementation of this, we just made the corresponding entry in types (we have used uriorcurie for cases were we need curies)

https://github.com/linkml/linkml-runtime/blob/a8b4dd14abab2eca48cd10a99b287077fcc2c55c/linkml_runtime/utils/metamodelcore.py#L148-L188