Add attachments for PR reviews (#16075)

* First step for multiple dropzones per page.

* Allow attachments on review comments.

* Lint.

* Fixed accidental initialize of the review textarea.

* Initialize SimpleMDE textarea.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

services/forms/repo_form.go

@@ -587,6 +587,7 @@ type SubmitReviewForm struct {
 	Content  string
 	Type     string `binding:"Required;In(approve,comment,reject)"`
 	CommitID string
+	Files    []string
 }
 
 // Validate validates the fields