rework and clean up backend

Handlers

• addAdmin
• admin
• auth
• findWish
• handler
• likeService
• likeWish
• media
• reminderMail
• service
• serviceUserGroup
• tag
• tagService
• tagWish
• userGroup
• user
• wish

Services

• admin
• auth
• likeService
• likeWish
• media
• reminder
• service
• serviceUserGroup (deleted)
• tag
• tagService (deleted)
• tagWish (deleted)
• userGroup (deleted)
• user
• wish