e2e: downstream mTLS

[arkodg]

Description:

Describe the issue.

Add an e2e for validating clients using a CA Cert as a trust anchor

Relates to https://github.com/envoyproxy/gateway/issues/88

[optional Relevant Links:]

Any extra documentation required to understand the issue.

[guydc]

Also consider testing additional variants of this feature, such as:

• Optional client certificate validation
• XFCC behavior and format

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had activity in the last 30 days.

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had activity in the last 30 days.