Add access token to user details endpoint (/.auth/me)

**Is your feature request related to a problem? Please describe.**
I'm using a custom identity provider and have the rolesSource set in the staticwebapp.config. Whenever a user logs in, a request gets sent to "/api/GetRoles" to assign roles to a user. All of this works perfectly and whenever I go to "/.auth/me" I have access to the roles, claims etc of the user.

The problem I'm facing is that the access token seems to be missing from the user details endpoint, and it's not a case of my identity provider not supplying the access token. I've setup azure application insights to inspect the request sent to "/api/GetRoles", and the principal sent in the body of the request clearly contains the access token. It's frustrating that the only place the access token is accessible, is an endpoint that must return "roles" and is not accessible after the initial call when a user logs in.

**Describe the solution you'd like**
I would like for the access token to be present whenever I send a request to the user details endpoint (/.auth/me).

**Describe alternatives you've considered**
I tried setting up a function called GetAccessToken that would retrieve the access token from the "x-ms-client-principal" header, but whenever I made a request to /api/GetAccessToken, the only information available in the "x-ms-client-principal" header is an object with the following properties:
- IdentityProvider
- UserId
- UserDetails
- UserRoles

There is unfortunately no access to claims or the access token in this client principal, like there is in the request body of the "/api/GetRoles" call.