Move name of message threads

`uco-observable:displayName` is not associated with
`uco-observable:MessageThreadFacet` by a SHACL property shape, at the
time of UCO 1.3.0.

Nothing encoded in UCO disallows the way it was used in `message.json`,
but the data stored in that property is being removed to follow the
suggestions from the SHACL shapes.

Reported in CASE-Mapping-Python PR 38.

No effects were observed on Make-managed files.

References:
* casework/CASE-Mapping-Python#38

Reported-by: Fabrizio Turchi <[email protected]>
Signed-off-by: Alex Nelson <[email protected]>

Author: ajnelson-nist

examples/illustrations/message/message.json

@@ -159,12 +159,12 @@
         {
             "@id": "kb:thread-4237ff8b-e049-4a56-bcf7-e89ed2797d83",
             "@type": "uco-observable:MessageThread",
+            "uco-core:name": "Best Friend Chat!!",
             "uco-core:hasFacet": [
                 {
                     "@id": "kb:message-thread-facet-33f68c51-0737-4716-8b2d-7612cd78a99b",
                     "@type": "uco-observable:MessageThreadFacet",
                     "identifier": "[email protected]",
-                    "uco-observable:displayName": "Best Friend Chat!!",
                     "uco-observable:visibility": false,
                     "uco-observable:messageThread": {
                         "@id": "kb:thread-c5b68f3b-a9a1-4595-9d54-b3fd3605871e",
@@ -240,12 +240,12 @@
         {
             "@id": "kb:thread-64330f59-a10d-4907-93f6-be9fc267834e",
             "@type": "uco-observable:MessageThread",
+            "uco-core:name": "Argle-bargle",
             "uco-core:hasFacet": [
                 {
                     "@id": "kb:message-thread-facet-38d3fc48-8519-40c5-98f3-d4ad4d42a867",
                     "@type": "uco-observable:MessageThreadFacet",
                     "identifier": "twitter_public",
-                    "uco-observable:displayName": "Argle-bargle",
                     "uco-observable:visibility": true,
                     "uco-observable:messageThread": {
                         "@id": "kb:thread-f8ebd1db-ce49-495e-850a-7b44187cb128",