Re-add Authentication Tests

[enuessle]

Re-added keyclock_test.go authentication tests.
Related to #432

[maia-iyer]

Thanks for this PR! I can't currently test this PR myself, but are you able to run the tests successfully?

[enuessle]

The tests run. One of the tests fails with this error for reasons I could not figure out myself.

--- FAIL: TestNewKeycloakAuthenticator (0.00s)
    keycloak_test.go:43: ERROR: could not create keyfunc from json: Could not set up OIDC Discovery client with issuer = '{"keys":[{"kty":"RSA","e":"AQAB","use":"sig","kid":"MjhhMDk2N2M2NGEwMzgzYjk2OTI3YzdmMGVhOGYxNjI2OTc5Y2Y2MQ","alg":"RS256","n":"zZU9xSgK77PbtkjJgD2Vmmv6_QNe8B54eyOV0k5K2UwuSnhv9RyRA3aL7gDN-qkANemHw3H_4Tc5SKIMltVIYdWlOMW_2m3gDBOODjc1bE-WXEWX6nQkLAOkoFrGW3bgW8TFxfuwgZVTlb6cYkSyiwc5ueFV2xNqo96Qf7nm5E7KZ2QDTkSlNMdW-jIVHMKjuEsy_gtYMaEYrwk5N7VoiYwePaF3I0_g4G2tIrKTLb8DvHApsN1h-s7jMCQFBrY4vCf3RBlYULr4Nz7u8G2NL_L9vURSCU2V2A8rYRkoZoZwk3a3AyJiqeC4T_1rmb8XdrgeFHB5bzXZ7EI0TObhlw"}]}': error fetching {"keys":[{"kty":"RSA","e":"AQAB","use":"sig","kid":"MjhhMDk2N2M2NGEwMzgzYjk2OTI3YzdmMGVhOGYxNjI2OTc5Y2Y2MQ","alg":"RS256","n":"zZU9xSgK77PbtkjJgD2Vmmv6_QNe8B54eyOV0k5K2UwuSnhv9RyRA3aL7gDN-qkANemHw3H_4Tc5SKIMltVIYdWlOMW_2m3gDBOODjc1bE-WXEWX6nQkLAOkoFrGW3bgW8TFxfuwgZVTlb6cYkSyiwc5ueFV2xNqo96Qf7nm5E7KZ2QDTkSlNMdW-jIVHMKjuEsy_gtYMaEYrwk5N7VoiYwePaF3I0_g4G2tIrKTLb8DvHApsN1h-s7jMCQFBrY4vCf3RBlYULr4Nz7u8G2NL_L9vURSCU2V2A8rYRkoZoZwk3a3AyJiqeC4T_1rmb8XdrgeFHB5bzXZ7EI0TObhlw"}]}/.well-known/openid-configuration: parse "{\"keys\":[{\"kty\":\"RSA\",\"e\":\"AQAB\",\"use\":\"sig\",\"kid\":\"MjhhMDk2N2M2NGEwMzgzYjk2OTI3YzdmMGVhOGYxNjI2OTc5Y2Y2MQ\",\"alg\":\"RS256\",\"n\":\"zZU9xSgK77PbtkjJgD2Vmmv6_QNe8B54eyOV0k5K2UwuSnhv9RyRA3aL7gDN-qkANemHw3H_4Tc5SKIMltVIYdWlOMW_2m3gDBOODjc1bE-WXEWX6nQkLAOkoFrGW3bgW8TFxfuwgZVTlb6cYkSyiwc5ueFV2xNqo96Qf7nm5E7KZ2QDTkSlNMdW-jIVHMKjuEsy_gtYMaEYrwk5N7VoiYwePaF3I0_g4G2tIrKTLb8DvHApsN1h-s7jMCQFBrY4vCf3RBlYULr4Nz7u8G2NL_L9vURSCU2V2A8rYRkoZoZwk3a3AyJiqeC4T_1rmb8XdrgeFHB5bzXZ7EI0TObhlw\"}]}/.well-known/openid-configuration": first path segment in URL cannot contain colon
FAIL
exit status 1
FAIL    github.com/spiffe/tornjak/pkg/agent/authentication/authenticator        0.003s