Enable code coverage comments on PRs in codecov configuration (#8402)

Fixes #7290.

### Description
Enable code coverage on PR checks on file diff.

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [x] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [x] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

Signed-off-by: Christopher Le <locvicvn1234@gmail.com>
Co-authored-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>

Author: chrislevn

.github/codecov.yml

@@ -24,8 +24,13 @@ coverage:
         flags: null
         paths: null
 
-# Disable comments on PR
-comment: false
+comment: # enable code coverage comment on PR
+  layout: "diff, flags, files"
+  behavior: default
+  require_changes: false
+  require_base: false
+  require_head: true
+  hide_project_coverage: true
 
 ignore:
   - "versioneer.py"