[v8] Allow CF Authentication based on Tokens - user and client tokens

[strehle]

(cherry picked from commit de83208)
PR from main: #3397

Description of the Change

Enhance the cf auth command with a parameter --assertion. The content of this token should be either a user token in order to perform a jwt-bearer or a client token in order to perform a client_credentials grant with federated trust.

UAA supports JWT bearer since UAA 4.5.0 , see https://docs.cloudfoundry.org/api/uaa/version/77.25.0/index.html#jwt-bearer-token-grant
UAA support the federated client credential flow since 77.25.0

Why Is This PR Valuable?

CF can be integrated into Github Action without any extra secret setup in Github Repo.
Customer can then decide about using external tokens like github action token for user and/or client authentication.

In a PR you retrieve a id_token from gh action, this can be passed with cf auth --assertion so that you are authentication in or to do a cf push ...

Applicable Issues

• Allow CF Authentication based on Tokens - user and client tokens #3368

How Urgent Is The Change?

• it is an enhancement but it solves security issues, because CF integrations need to omit secrets and/or client certificates, but integration of github action with CF is only possible if you store a secret in Github

Other Relevant Parties

Only CF landscapes with a configured trust to external OIDC parties