Adding groups to storage and cleaning up storage a bit

Signed-off-by: Ethan Wellenreiter <ewellenreiter@gmail.com>

backend/internal/storage/groups.go

@@ -0,0 +1,9 @@
+package storage
+
+type Group struct {
+	ID         int64   `json:"id"`
+	Name       string  `json:"name"`
+	Users      []int64 `json:"users"`
+	Owner      int64   `json:"owner"`
+	Moderators []int64 `json:"moderators"`
+}

backend/internal/storage/local_user.go

@@ -1 +0,0 @@
-package storage

backend/internal/storage/storage.go

@@ -9,13 +9,12 @@ type Storage struct {
 	Receipts interface {
 		GetByID(context.Context, int64) (*Receipt, error)
 	}
-	Users interface {
-		AddUser(user string, password string) error
-		RemoveUser(user string, password string) error
-		UpdateUserPass(user string, oldPassword string, newPass string) error
-	}
 	Images interface {
 		GetByID(context.Context, int64) (*Image, error)
+		RemoveByID(context.Context, int64) (*Image, error)
+	}
+	Groups interface {
+		GetByID(context.Context, int64)
 	}
 }