feat: specify login UI version on instance and apps (#9071)

# Which Problems Are Solved

To be able to migrate or test the new login UI, admins might want to
(temporarily) switch individual apps.
At a later point admin might want to make sure all applications use the
new login UI.

# How the Problems Are Solved

- Added a feature flag `` on instance level to require all apps to use
the new login and provide an optional base url.
- if the flag is enabled, all (OIDC) applications will automatically use
the v2 login.
  - if disabled, applications can decide based on their configuration
- Added an option on OIDC apps to use the new login UI and an optional
base url.
- Removed the requirement to use `x-zitadel-login-client` to be
redirected to the login V2 and retrieve created authrequest and link
them to SSO sessions.
- Added a new "IAM_LOGIN_CLIENT" role to allow management of users,
sessions, grants and more without `x-zitadel-login-client`.

# Additional Changes

None

# Additional Context

closes https://github.com/zitadel/zitadel/issues/8702

internal/query/oidc_client_by_id.sql

@@ -3,7 +3,8 @@ with client as (
 		c.app_id, a.state, c.client_id, c.back_channel_logout_uri, c.client_secret, c.redirect_uris, c.response_types,
 		c.grant_types, c.application_type, c.auth_method_type, c.post_logout_redirect_uris, c.is_dev_mode,
 		c.access_token_type, c.access_token_role_assertion, c.id_token_role_assertion,
-		c.id_token_userinfo_assertion, c.clock_skew, c.additional_origins, a.project_id, p.project_role_assertion
+		c.id_token_userinfo_assertion, c.clock_skew, c.additional_origins, a.project_id, p.project_role_assertion,
+		c.login_version, c.login_base_uri
 	from projections.apps7_oidc_configs c
 	join projections.apps7 a on a.id = c.app_id and a.instance_id = c.instance_id and a.state = 1
 	join projections.projects4 p on p.id = a.project_id and p.instance_id = a.instance_id and p.state = 1