chore(tests): add coverage for ./pkg/runner (#202)

Only changes test files.

---

- remove tests specific to running on a host with no container
  they are the same as with the containers (TestRunEventHostEnvironment)
- prefix the name of the tests with a distinctive name to
  more easily run them together
- use code.forgejo.org/oci images whereever possible
- remove some tests that are either
  - difficult to understand (ancient bugs)
  - not yet well understood (related to reusable workflows)
  - depend on github (generation of workflows to be run on the fly
    e.g. updateTestIfWorkflow)
- fix the TestSanitizeNetworkAlias tests that were not run
  and make them easier to debug
- disable tests of options that are forbidden in Forgejo Actions
  (testdata/container-hostname/push.yml)

Reviewed-on: https://code.forgejo.org/forgejo/act/pulls/202
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

act/runner/action_cache_test.go

@@ -19,7 +19,7 @@ func TestActionCache(t *testing.T) {
 	}
 	ctx := context.Background()
 	cacheDir := "nektos/act-test-actions"
-	repo := "https://github.com/nektos/act-test-actions"
+	repo := "https://code.forgejo.org/forgejo/act-test-actions"
 	refs := []struct {
 		Name     string
 		CacheDir string