Post code coverage diff comments for AzDO PRs

Author: AArnott

azurepipelines-coverage.yml

@@ -0,0 +1,6 @@
+# https://learn.microsoft.com/azure/devops/pipelines/test/codecoverage-for-pullrequests?view=azure-devops
+coverage:
+  status:
+    comments: on    # add comment to PRs reporting diff in coverage of modified files
+    diff:           # diff coverage is code coverage only for the lines changed in a pull request.
+      target: 70%   # set this to a desired %. Default is 70%