* Optimize policy iterators (go1.23)
This modifies (*Options).GetAllPolicies() to use a go 1.23 iterator
instead of copying all policies on every call, which can be extremely
expensive. All existing usages of this function were updated as
necessary.
Additionally, a new (*Options).NumPolicies() method was added which
quickly computes the number of policies that would be given by
GetAllPolicies(), since there were several usages where only the
number of policies was needed.
* Fix race condition when assigning default envoy opts to a policy
* proxy: support re-proxying request from envoy for kubernetes
* encrypt policy id for reproxy, implement tls options
* add comment, use hmac
* use httputil handler and error
* remove reproxy headers on all incoming request
* only allow re-proxying for kubernetes, strip headers
* fix tests
