test: allow selectively running tests for remotes (#4920)

Some of the tests are run by default, other requires
`--enable-{remote}` to run. The remotes that are run by default
also have a `--disable-{remote}` flag. All of the remotes can be
enabled using `--all` flag.

To use this functionality in the fixture,
`test_config` fixture has to be used, and requires to call
`test_config.requires(remote)`.
In an individual test, you can simply use `pytest.mark.remote`
to make them skip or run.

.github/workflows/tests.yaml

@@ -65,7 +65,7 @@ jobs:
         mkdir -p scripts/ci
         echo "$GS_CREDS_JSON" > scripts/ci/gcp-creds.json
     - name: run tests
-      run: python -m tests -ra --cov-report=xml --cov-report=term --tap-combined
+      run: python -m tests --all -ra --cov-report=xml --cov-report=term --tap-combined
     - name: upload coverage report
       uses: codecov/[email protected]
       with: