Add route to allow users to upload/delete site images

[fzyang1227]

Why

• allow users to upload real images of the tree

What to do

• Documentation: https://docs.c4cneu.com/sftt/sftt-api-spec/#upload-site-image-admin-and-owner-only

• See below for reference (it will be similar to this): https://github.com/Code-4-Community/lucys-love-bus-backend/blob/028af3af0c70f6155751d2346d721bd28c1bf48d/service/src/main/java/com/codeforcommunity/processor/EventsProcessorImpl.java#L68-L69

Reach out to Kenny for any questions.

• There's already an existing route that takes in a valid URL and sets it to be the site's image. Instead, change this route to take in the base 64 encoded string of the image, upload it to the S3 bucket (referring to the above link for reference), and adds the new image's S3 bucket URL as a new row in the site image table.

Right now

• Takes in a s3 url (AWS storage)
• Images specifically ...
• route takes in: s3 url, retrieves it (image had already been uploaded manually)
• Automate process of uploading image, generating url
  • Maybe when uploading get url
• Then store url in database (tbd ... ticket to be merged)
• Separate ticket to get site information would include getting image from s3

[huang0h]

Resolved by #191