Coveralls workflow applied also to stable (#342)

* Coveralls (#339)

* Add code coverage report as part of the workflows

* Remove -Clink-dead-code which seems to be problematic

* Manually set features to avoid debug_* failing unit tests.

* Update badges

* Add libraries directory to trigger code coverage reporting.

* Fix coveralls badge not pointing to the branch

* Badges to stable branch

.github/actions-rs/grcov.yml

@@ -0,0 +1,9 @@
+branch: true
+ignore-not-existing: true
+llvm: true
+filter: covered
+output-type: lcov
+output-path: ./lcov.info
+ignore:
+  - "third_party/*"
+  - "/*"