This flag is (for now) meant only to facilitate end-to-end testing, allowing us to force the "manual" login flow. If it ends up being useful we can un-hide it, but this seemed like the safest option to start with.
There is also a corresponding `--oidc-skip-listen` on the `pinniped get kubeconfig` command.
Signed-off-by: Matt Moyer <moyerm@vmware.com>