feat(coap): Support both PKI and PSK being configured concurrently (IEC-78)

[mrdeep1]

Checklist

• [ ] Component contains License
• [ ] Component contains README.md
• [ ] Component contains idf_component.yml file with url field defined
• [ ] Component was added to upload job
• [ ] Component was added to build job
• [ ] Optional: Component contains unit tests
• [ ] CI passing

Change description

Addresses #285

[hmalpani]

Thanks for updating the PR. I think the certificates also needs to updated. I am getting these logs with only PKI enabled:

I (12442) CoAP_client:    0.0.0.0:60719 <-> 20.47.97.44:5684 DTLS: The certificate is not correctly signed by the trusted CA: issue 0x8: 'cf-ca' depth 1
I (12452) CoAP_client: *  0.0.0.0:60719 <-> 20.47.97.44:5684 DTLS: netif: sent   15 bytes
I (12462) CoAP_client: do_mbedtls_handshake: session establish returned 'X509 - Certificate verification failed, e.g. CRL, CA or signature check failed'
I (12472) CoAP_client: ***EVENT: COAP_EVENT_DTLS_ERROR

[mrdeep1]

Will check. Looks like it is californium.eclipseprojects.io certificates have been updated. Will try to find the updated ones.

[mrdeep1]

Certificates updated.

[hmalpani]

@mahavirj should we also bump up the version in example idf_component.yml file?

[mrdeep1]

I did bump the version of idf_component.yml in this PR.