Fix/Avoid duplicate app interface creation + clean-up

[JettTech]

Updates:

• Renames HHAAgent to CoreAppAgent
• Adds the clone trait to CoreAppAgent and HfAgent.
• Adds check in AppConnection.connect() to avoid attaching new app interfaces for app interfaces that already exist

NB: This is needed in holo-matching-services
matching services pr: https://github.com/Holo-Host/holo-matching-services/pull/53

[JettTech]

@zo-el - CI tests are failing the the devNet and alphaNet runs of the run_configure_holochain test due an error fetching the membrane proof from the memproof server. The call to the memproof server is responding with a 502 (Bad Gateway) error. This error seems to be intermittently occurring across multiple PRs. NB: It is passing on the read-only memproof test of the same function.

Do you have any ideas about what is causing the memproof server to return this error? If not, I can just bring this issue up at PL tomorrow.

Also, with all this in mind, this PR is ready for your review.

[zo-el]

Also, small reminder to update all println to debug logs