Please add support for configuring token_endpoint_auth_method

[zakhenry]

Describe the problem you'd like to have solved

I interact with an oidc implementation that only has support for the client_secret_basic option for token_endpoint_auth_method which means I cannot use the playground to test with as the playground supports only client_secret_post

Describe the ideal solution

The playground could have a dropdown to select the token endpoint auth method (ideally prefilled by inspecting the .well-known/openid-configuration endpoint)

Options outlined in https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderMetadata

Alternatives and current work-arounds

No alternatives if the implementation doesn't support the mechanism