* [gitpod-db] Add `d_b_oidc_client_config.active` field
* [papi] Add OIDCClientConfig.active to proto def
* [gitpod-db] Add OIDCClientConfig.active
* [papi] Add `activate` param to `/oidc/start` endpoint handler
If provided it should mark the OIDC client config as `active` in the DB.
* Fix propagation of state params and add tests.
* fix import of deprecated ioutil
* refactor GetStartParams
* consider `activate` from create request
Using JWT tokens for encoding/decoding/validation of state params carried throughout the OIDC/OAuth2 flow.
Validating of integrity is crucial, as this piece of information contains the ID of the OIDC client to continue with when Gitpod receives the callback from a 3rd party. Tests should show that expiration time is checked and signature validation is effective.
