[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)

services/issue/comments.go

@@ -66,6 +66,11 @@ func CreateRefComment(doer *user_model.User, repo *repo_model.Repository, issue
 
 // CreateIssueComment creates a plain issue comment.
 func CreateIssueComment(ctx context.Context, doer *user_model.User, repo *repo_model.Repository, issue *issues_model.Issue, content string, attachments []string) (*issues_model.Comment, error) {
+	// Check if doer is blocked by the poster of the issue.
+	if user_model.IsBlocked(ctx, issue.PosterID, doer.ID) {
+		return nil, user_model.ErrBlockedByUser
+	}
+
 	comment, err := CreateComment(ctx, &issues_model.CreateCommentOptions{
 		Type:        issues_model.CommentTypeComment,
 		Doer:        doer,