4689 multi workspace i should be able to accept an invite if im already logged in (#5454)

- split signInUp to separate Invitation from signInUp
- update redirection logic
- add a resolver for userWorkspace
- add a mutation to add a user to a workspace
- authorize /invite/hash while loggedIn
- add a button to join a workspace

### Base functionnality

https://github.com/twentyhq/twenty/assets/29927851/a1075a4e-a2af-4184-aa3e-e163711277a1

### Error handling

https://github.com/twentyhq/twenty/assets/29927851/1bdd78ce-933a-4860-a87a-3f1f7bda389e

packages/twenty-front/src/modules/workspace-member/grapqhql/mutations/addUserToWorkspace.ts

@@ -0,0 +1,9 @@
+import { gql } from '@apollo/client';
+
+export const ADD_USER_TO_WORKSPACE = gql`
+  mutation AddUserToWorkspace($inviteHash: String!) {
+    addUserToWorkspace(inviteHash: $inviteHash) {
+      id
+    }
+  }
+`;