refactor: replace refresh & access token with auth token only

changes authentication to no longer use a refresh token & access token
for accessing protected endpoints. Instead only an auth token is used.

Before the login flow was:

Login -> get refresh (stored as HttpOnly cookie) + access token (stored in memory) ->
  protected endpoint request (attach access token as Authorization header) -> access token expires in
  15 minutes, so use refresh token to obtain new one when that happens

now it looks like this:

Login -> get auth token (stored as HttpOnly cookie) -> make protected endpont
request (token sent)

the reasoning for using the refresh + access token was to reduce DB
calls, but in the end I don't think its worth the hassle.

internal/graph/schema/user.gql

@@ -1,5 +1,4 @@
 extend type Mutation {
-  createRefreshToken(input: NewRefreshToken!): RefreshToken!
   createUserAccount(input: NewUserAccount!):
     UserAccount! @hasRole(roles: [ADMIN], level: ORG, type: ORG)
   deleteUserAccount(input: DeleteUserAccount!):
@@ -72,10 +71,6 @@ type UpdateUserRolePayload {
   user: UserAccount!
 }
 
-input NewRefreshToken {
-  userID: UUID!
-}
-
 input NewUserAccount {
   username: String!
   email: String!