Lambda filter overhaul - Githubissues

Now that upstream has also implemented their own lambda filter there are some really nice improvements that we can emulate.

Ideally we would align closer to upstream and slot our authentication and transformation improvements.

TODO: @nfuden link the changes such as:

[ ] splitting out signing to not be lambda specific
[ ] allow lambdas signing to happen later as an http extension so that transforms dont mess up signing

solo-io / envoy-gloo