support macros in encryption fields for certificates and pre-shared keys

It would be nice if "PSK identity", "PSK, "Issuer", and "Subject" fields in host's "Encryption" tab would support macros, allowing for simpler configuration.

For instance, "PSK identity" could be "psk-id-{HOST.HOST}" or "Subject" could be "CN={HOST.HOST}" (after ZBXNEXT-3144 is implemented).