[MODERATION] user blocking

- Add the ability to block a user via their profile page.
- This will unstar their repositories and visa versa.
- Blocked users cannot create issues or pull requests on your the doer's repositories (mind that this is not the case for organizations).
- Blocked users cannot comment on the doer's opened issues or pull requests.
- Blocked users cannot add reactions to doer's comments.
- Blocked users cannot cause a notification trough mentioning the doer.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/540
(cherry picked from commit 687d852480)
(cherry picked from commit 0c32a4fde5)
(cherry picked from commit 1791130e3c)
(cherry picked from commit 37858b7e8f)
(cherry picked from commit a3e2bfd7e9)
(cherry picked from commit 7009b9fe87)

Conflicts: https://codeberg.org/forgejo/forgejo/pulls/1014
	routers/web/user/profile.go
	templates/user/profile.tmpl

models/user/block.go

@@ -0,0 +1,78 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package user
+
+import (
+	"context"
+	"errors"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+// ErrBlockedByUser defines an error stating that the user is not allowed to perform the action because they are blocked.
+var ErrBlockedByUser = errors.New("user is blocked by the poster or repository owner")
+
+// BlockedUser represents a blocked user entry.
+type BlockedUser struct {
+	ID int64 `xorm:"pk autoincr"`
+	// UID of the one who got blocked.
+	BlockID int64 `xorm:"index"`
+	// UID of the one who did the block action.
+	UserID int64 `xorm:"index"`
+
+	CreatedUnix timeutil.TimeStamp `xorm:"created"`
+}
+
+// TableName provides the real table name
+func (*BlockedUser) TableName() string {
+	return "forgejo_blocked_user"
+}
+
+func init() {
+	db.RegisterModel(new(BlockedUser))
+}
+
+// IsBlocked returns if userID has blocked blockID.
+func IsBlocked(ctx context.Context, userID, blockID int64) bool {
+	has, _ := db.GetEngine(ctx).Exist(&BlockedUser{UserID: userID, BlockID: blockID})
+	return has
+}
+
+// IsBlockedMultiple returns if one of the userIDs has blocked blockID.
+func IsBlockedMultiple(ctx context.Context, userIDs []int64, blockID int64) bool {
+	has, _ := db.GetEngine(ctx).In("user_id", userIDs).Exist(&BlockedUser{BlockID: blockID})
+	return has
+}
+
+// UnblockUser removes the blocked user entry.
+func UnblockUser(ctx context.Context, userID, blockID int64) error {
+	_, err := db.GetEngine(ctx).Delete(&BlockedUser{UserID: userID, BlockID: blockID})
+	return err
+}
+
+// ListBlockedUsers returns the users that the user has blocked.
+func ListBlockedUsers(ctx context.Context, userID int64) ([]*User, error) {
+	users := make([]*User, 0, 8)
+	err := db.GetEngine(ctx).
+		Select("`user`.*").
+		Join("INNER", "forgejo_blocked_user", "`user`.id=`forgejo_blocked_user`.block_id").
+		Where("`forgejo_blocked_user`.user_id=?", userID).
+		Find(&users)
+
+	return users, err
+}
+
+// ListBlockedByUsersID returns the ids of the users that blocked the user.
+func ListBlockedByUsersID(ctx context.Context, userID int64) ([]int64, error) {
+	users := make([]int64, 0, 8)
+	err := db.GetEngine(ctx).
+		Table("user").
+		Select("`user`.id").
+		Join("INNER", "forgejo_blocked_user", "`user`.id=`forgejo_blocked_user`.user_id").
+		Where("`forgejo_blocked_user`.block_id=?", userID).
+		Find(&users)
+
+	return users, err
+}