refactor(jans-cedarling): relocate tokens from context to user and workload entities

[rmarinn]

Is your feature request related to a problem? Please describe.

In the current implementation, tokens such as access_token, id_token, and userinfo_token are included in the Context entity. To simplify policy definitions and improve clarity, we can move the access_token to the Workload entity and relocating the id_token and userinfo_token to the User entity. This change directly associates tokens with their respective owners, making policies easier to express.

Describe the solution you'd like

We need to update the schema:

entity Workload = {
    "client_id": String,
    "iss": TrustedIssuer,
    "name"?: String,
    "rp_id"?: String,
    "spiffe_id"?: String,
    "access_token"?: Access_token,    // Moved from Context
    "id_token"?: id_token,    // Moved from Context
};
entity User in [Role] = {
    "email"?: email_address,
    "phone_number"?: String,
    "role": Set<String>,
    "sub": String,
    "username"?: String,
    "id_token"?: id_token,    // Moved from Context
    "userinfo_token"?: userinfo_token,    // Moved from Context
};

Describe alternatives you've considered
N/A

Additional context
N/A