Describe the feature request
Support first party JWT for platforms that do not have third party JWTs (e.g., Kubernetes with versions < 1.13).

Describe alternatives you've considered
Istio does not support first party JWT.

[ ] Configuration Infrastructure
[ ] Docs
[ ] Installation
[X ] Networking
[ ] Performance and Scalability
[ ] Policies and Telemetry
[ X] Security
[ ] Test and Release
[ ] User Experience
[ ] Developer Infrastructure

Additional context