Read certificates from secrets to setup TLS config for route trait

[claudio4j]

Currently route trait parameters tls-certificate, tls-key, tls-ca-certificate, tls-destination-ca-certificate expects certificates to set as string parameters, but that is a difficult to set as command line parameters, example:

-t route.tls-key="-----BEGIN RSA PRIVATE KEY-----MIIEowIBAA..."

This is a proposal to read certificates from secrets to setup TLS configuration for route trait.

[squakez]

With this approach, the certificates may be provided with different means (ie, volumes mounted) as well.