Accept certificate with prompt

In other parts of Gateway it will pop up with something that lets you accept the cert and add it to the trust store. Can we do that for our client too instead of making the user do it manually?

We also have a setting for adding a path to a CA, but seems reasonable to add this if the rest of Gateway is doing it.

**Edit**: `CertificateManager.getInstance().sslContext`. Should this replace the settings we have? Maybe this stuff should be managed by Gateway itself.