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/setting/moderation.go

@@ -0,0 +1,15 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package setting
+
+// Moderation settings
+var Moderation = struct {
+	Enabled bool `ini:"ENABLED"`
+}{
+	Enabled: false,
+}
+
+func loadModerationFrom(rootCfg ConfigProvider) {
+	mustMapSetting(rootCfg, "moderation", &Moderation)
+}