feat!: Abusive content reporting (#6977)

This implements milestones 1. and 4. from **Task F. Moderation features: Reporting** (part of [amendment of the workplan](https://codeberg.org/forgejo/sustainability/src/branch/main/2022-12-01-nlnet/2025-02-07-extended-workplan.md#task-f-moderation-features-reporting) for NLnet 2022-12-035):

> 1. A reporting feature is implemented in the database. It ensures that content remains available for review, even if a user deletes it after a report was sent.

> 4. Users can report the most relevant content types (at least: issue comments, repositories, users)

### See also:
- forgejo/discussions#291
- forgejo/discussions#304
- forgejo/design#30

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6977
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: floss4good <floss4good@disroot.org>
Co-committed-by: floss4good <floss4good@disroot.org>

modules/repository/create.go

@@ -1,4 +1,5 @@
 // Copyright 2019 The Gitea Authors. All rights reserved.
+// Copyright 2024 The Forgejo Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
 package repository
@@ -241,6 +242,11 @@ func UpdateRepository(ctx context.Context, repo *repo_model.Repository, visibili
 
 	e := db.GetEngine(ctx)
 
+	// If the repository was reported as abusive, a shadow copy should be created before first update.
+	if err := repo_model.IfNeededCreateShadowCopyForRepository(ctx, repo, true); err != nil {
+		return err
+	}
+
 	if _, err = e.ID(repo.ID).AllCols().Update(repo); err != nil {
 		return fmt.Errorf("update: %w", err)
 	}