proxy: v2.87.0 (#4110)

This release comprises many internal changes that are not expected to
have any user-facing impact.

There is one user-facing change: the inbound router's default capacity
has been increased from 100 to 10K to accomodate environments that have
a high cardinality of virtual hosts served by a single pod.

---

* fallback: Operate on Services instead of Layers (linkerd/linkerd2-proxy#432)
* internal: Extract a service-profile crate (linkerd/linkerd2-proxy#433)
* Increase inbound router capacity default to 10000 (linkerd/linkerd2-proxy#434)
* Upgrade to Rust 1.41 (linkerd/linkerd2-proxy#437)
* cleanup: Remove various cruft (linkerd/linkerd2-proxy#438)
* Generalize router::Make as stack::NewService (linkerd/linkerd2-proxy#435)
* integration: Make the test controller more realistic (linkerd/linkerd2-proxy#436)
* trace-context: Remove unnecessary MakeService (linkerd/linkerd2-proxy#439)
* Split the `stack-tracing` crate from `app-core` (linkerd/linkerd2-proxy#440)
* stack: Introduce the Proxy trait (linkerd/linkerd2-proxy#441)
* timeout: Do not synthesize HTTP response (linkerd/linkerd2-proxy#442)
* addr: Avoid trailing dots in authorities (linkerd/linkerd2-proxy#446)
* outbound: Relax type constraints in require_identity_on_endpoint (linkerd/linkerd2-proxy#447)
* Cleanup transport::Connect & http::Client types (linkerd/linkerd2-proxy#443)
* app: Use locks with controller clients (linkerd/linkerd2-proxy#448)