Add route for group imports via the UI

Group imports via the UI has been implemented in the GitLab application
as part of https://gitlab.com/gitlab-org/gitlab/-/merge_requests/29270.
Ensure that the workhorse configuration is setup for this at the same
time.

Relates to: https://gitlab.com/gitlab-org/gitlab/-/issues/211807

changelogs/unreleased/jh-group_import_ui.yml

+---
+title: Add routes for Group import via the UI
+merge_request: 493
+author:
+type: added

internal/upstream/routes.go

@@ -227,6 +227,8 @@ func (u *upstream) configureRoutes() {
 
 		// Project Import via UI upload acceleration
 		route("POST", importPattern+`gitlab_project`, upload.Accelerate(api, signingProxy)),
+		// Group Import via UI upload acceleration
+		route("POST", importPattern+`gitlab_group`, upload.Accelerate(api, signingProxy)),
 
 		// Explicitly proxy API requests
 		route("", apiPattern, proxy),

upload_test.go

@@ -124,6 +124,7 @@ func TestAcceleratedUpload(t *testing.T) {
 		{"POST", `/api/v4/groups/import`, true},
 		{"POST", `/api/v4/projects/import`, true},
 		{"POST", `/import/gitlab_project`, true},
+		{"POST", `/import/gitlab_group`, true},
 		{"POST", `/api/v4/projects/9001/packages/pypi`, true},
 	}