Create CODEOWNERS file (#74)

* Create CODEOWNERS file

Create CODEOWNERS file to include 1ES:SDL Engineering team

* Update CODEOWNERS

.github/CODEOWNERS

@@ -0,0 +1,5 @@
+# Code owners file.
+# This file controls who is tagged for review for any given pull request.
+
+# For anything not explicitly taken by someone else:
+*       @microsoft/1es-sdl-engineering