Create GraphQL resolver for firebase profile photo uploads

[neelismail01]

Summary and Background

Create a GraphQL resolver to enable profile photos uploaded by volunteers to be stored, removed, and retrieved from Firebase. This logic is used for the following mockup:

Technical

• backend/services/implementation/fileStorageService.ts supports all interactions with Firebase Storage, so this file will be useful for this ticket
• You will need to create queries and mutations in backend/graphql/resolvers/userResolvers.ts-createFilefor uploading -deleteFilefor deleting -getFile` for retrieving
• Our naming convention for profile pictures will be 'volunteers/profile-photo/[hash of volunteer email]'. The client will send the volunteer's email with their request for the profile picture, so you will need to hash it and then append it to the picture's path to get the correct file name for retrieval. Similarly, for uploading a file, the fileName parameter passed to createFile will be the hash of the volunteer's email, and the path will be 'volunteers/profile-photo'.