## Summary
Update the `RouteID` to use the `policy.ID` if it is set. This makes it
so that updated routes use a stable identifier between updates so if the
envoy control plane is updated before the authorize service's internal
definitions (or vice-versa) the authorize service will still be able to
match the route.
The current behavior results in a 404 if envoy passes the old route id.
The new behavior will result in inconsistency, but it should be quickly
remedied. To help with debugging 4 new fields were added to the
authorize check log. The `route-id` and `route-checksum` as the
authorize sees it and the `envoy-route-id` and `envoy-route-checksum` as
envoy sees it.
I also updated the way we send updates to envoy to try and model their
recommended approach:
> In general, to avoid traffic drop, sequencing of updates should follow
a make before break model, wherein:
>
> - CDS updates (if any) must always be pushed first.
> - EDS updates (if any) must arrive after CDS updates for the
respective clusters.
> - LDS updates must arrive after corresponding CDS/EDS updates.
> - RDS updates related to the newly added listeners must arrive after
CDS/EDS/LDS updates.
> - VHDS updates (if any) related to the newly added RouteConfigurations
must arrive after RDS updates.
> - Stale CDS clusters and related EDS endpoints (ones no longer being
referenced) can then be removed.
This should help avoid 404s when configuration is being updated.
## Related issues
-
[ENG-2386](https://linear.app/pomerium/issue/ENG-2386/large-number-of-routes-leads-to-404s-and-slowness)
## Checklist
- [x] reference any related issues
- [x] updated unit tests
- [x] add appropriate label (`enhancement`, `bug`, `breaking`,
`dependencies`, `ci`)
- [x] ready for review
This also replaces instances where we manually write "return ctx.Err()"
with "return context.Cause(ctx)" which is functionally identical, but
will also correctly propagate cause errors if present.
* use incremental API
* add test
* use backoff v4
* remove panic, add comment to exponential try, add test for HashProto
* merge master
* fix missing import
