make it easier to understand check connection errors

[jrhizor]

It needs to be easy for users to understand why connection checks are failing. Usually these failures are caused by inability access a host/port/db/api due to networking, credentials, etc.

Possible short term fix:
Expose failure logs in the UI so it's easy to debug why the connection failed. Right now this is accessible from docker-compose up logs or by viewing the persisted logs for the connection check job, but that is not easy to use.

Possible long term fix:
Allow the integration to map errors to specific fields alongside a custom connection error.

[cgardens]

i think this is handled by the new changes in FE. putting it in milestone so that we make sure it is actually done.

[cgardens]

This is in progress in this issue: #1121. going to close as duplicate.