Allow sidecars to Tyk Gateway

[vanny96]

There are some instances where it would be beneficial to deploy sidecars together with Tyk Gateway. One such instance is, for example, when we want to deploy a tyk GRPC plugin.

Deploying it as a side car would guarantee that the 2 scale together, and that the latency is as low as it can get.

At this time, it seems like there is no support for sidecars, could it be added?