Fix bug with naming after new registry refactor (Bears-R-Us#2722)

unregister an array when that `name` field isn't set when creating
registry entries. To get around that, in the initializers, the name
field needs to be set. This PR handles that for the `ArrayRegEntry`,
which was causing testing failures, but there are other types that
have multiple names where it isn't as clear what "name" should be.
I suspect those cases need to be fixed as well.

src/MultiTypeRegEntry.chpl

@@ -70,6 +70,7 @@ module MultiTypeRegEntry {
         proc init(array_name: string, objType: ObjType) {
             super.init(objType);
             this.array = array_name;
+            this.name = array_name;
         }
 
         proc asMap(st: borrowed SymTab): map(string, string) throws {
@@ -96,6 +97,7 @@ module MultiTypeRegEntry {
             this.array = array_name;
             this.width = width;
             this.reverse = reverse;
+            this.name = array_name;
         }
 
         proc asMap(st:borrowed SymTab): map(string, string) throws {