chore: import the ACT test workflow

- remove go vet and build as they are now redundant
- replace ./pkg with ./act
- rename the workflow from test to act to distinguish it from the
  runner workflow

cleanup and factorization with the runner workflow is left for later

act/runner/run_context_test.go

@@ -318,7 +318,7 @@ func TestRunContext_GetGitHubContext(t *testing.T) {
 		actor = a
 	}
 
-	repo := "forgejo/act"
+	repo := "forgejo/runner"
 	if r := os.Getenv("ACT_REPOSITORY"); r != "" {
 		repo = r
 	}

act/runner/step_action_local_test.go

@@ -262,7 +262,7 @@ func TestStepActionLocalPost(t *testing.T) {
 						return strings.HasSuffix(array[1], suffix)
 					})
 				}
-				cm.On("Exec", suffixMatcher("pkg/runner/local/action/post.js"), sal.env, "", "").Return(func(ctx context.Context) error { return tt.err })
+				cm.On("Exec", suffixMatcher("act/runner/local/action/post.js"), sal.env, "", "").Return(func(ctx context.Context) error { return tt.err })
 
 				cm.On("Copy", "/var/run/act", mock.AnythingOfType("[]*container.FileEntry")).Return(func(ctx context.Context) error {
 					return nil