Add TLS decryption to HTTP proxy

[SerialVelocity]

Is this a BUG or FEATURE REQUEST?:
FEATURE REQUEST

Did you review istio.io/help and existing issues to identify if this is already solved or being worked on?:
Y

Feature Request:
Y

Describe the feature:
While using the HTTP proxy, it would be nice to be able to decrypt traffic so that L7 filters can be used.

This may require adding a second port for an HTTPS proxy if support is wanted for both https and http traffic.
Adding an SSLContext block to the HTTP proxy means that all incoming traffic is treated as HTTPS traffic.

[louiscryan]

Can you retest with 0.8. We have specific support for TLS termination in our revised API for Gateway (Ingress)

[SerialVelocity]

Sorry, I think I didn't explain it well enough. In our Istio configuration we set proxyHttpPort: 9531 which enables the HTTP proxy in Istio rather than Istio intercepting traffic using iptables. It would be nice if there was a proxyHttpsPort which intercepts outgoing encrypted traffic with a given cert.