Gep 2907 update - TLS mode and allowed routes

[mlavacca]

What type of PR is this?

/kind gep

What this PR does / why we need it:

This PR supersedes #3190.

This PR updates GEP-2907 with two different aspects:

• definition of TLS mode (Terminate and Passthrough)
• what routes can be attached to Listeners that specify TLS configuration.

This PR intends to reach an agreement that will make #2111 and #1474 addressable.

Which issue(s) this PR fixes:

Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

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[mlavacca]

/cc @candita @youngnick

[youngnick]

Yeah, this accurately conveys the current state, although I think that we do not have any conformance testing at all about TLSRoute with Terminate behavior.

Edit LGTM, but I'd like to hear from others too.

[mlavacca]

Yeah, this accurately conveys the current state, although I think that we do not have any conformance testing at all about TLSRoute with Terminate behavior.

Edit LGTM, but I'd like to hear from others too.

Yep, I just created #3466 to track conformance tests with TLSRoutes in Terminate Mode.