This table holds associations between uploads and other models. This can be used to prevent removing uploads that are still in use.
* DEV: Create upload_references
* DEV: Use UploadReference instead of PostUpload
* DEV: Use UploadReference for SiteSetting
* DEV: Use UploadReference for Badge
* DEV: Use UploadReference for Category
* DEV: Use UploadReference for CustomEmoji
* DEV: Use UploadReference for Group
* DEV: Use UploadReference for ThemeField
* DEV: Use UploadReference for ThemeSetting
* DEV: Use UploadReference for User
* DEV: Use UploadReference for UserAvatar
* DEV: Use UploadReference for UserExport
* DEV: Use UploadReference for UserProfile
* DEV: Add method to extract uploads from raw text
* DEV: Use UploadReference for Draft
* DEV: Use UploadReference for ReviewableQueuedPost
* DEV: Use UploadReference for UserProfile's bio_raw
* DEV: Do not copy user uploads to upload references
* DEV: Copy post uploads again after deploy
* DEV: Use created_at and updated_at from uploads table
* FIX: Check if upload site setting is empty
* DEV: Copy user uploads to upload references
* DEV: Make upload extraction less strict
