Merged in task/dspace-cris-2023_02_x/DSC-2734 (pull request DSpace#4123)

[DSC-2734] added CORE label to en.json5

Approved-by: Mykhaylo Boychuk

Author: Tnnienn

src/assets/i18n/en.json5

@@ -6059,6 +6059,8 @@
 
   "submission.import-external.source.pubmed": "Pubmed",
 
+  "submission.import-external.source.core": "CORE",
+
   "submission.import-external.source.pubmedeu": "Pubmed Europe",
 
   "submission.import-external.source.lcname": "Library of Congress Names",