feat(wfe-server): gRPC reflection, auto-generated schema endpoints, Dockerfile

- tonic-reflection for gRPC service discovery
  - /schema/workflow.json (JSON Schema from schemars derives)
  - /schema/workflow.yaml (same schema in YAML)
  - /schema/workflow.proto (raw proto file)
  - Multi-stage alpine Dockerfile with all executor features
  - Comprehensive configuration reference (wfe-server/README.md)
  - Release script (scripts/release.sh)
  - Bumped to 1.8.1

wfe-server-protos/src/lib.rs

@@ -15,3 +15,6 @@ include!(concat!(env!("OUT_DIR"), "/mod.rs"));
 pub use prost;
 pub use prost_types;
 pub use tonic;
+
+/// Encoded file descriptor set for gRPC reflection.
+pub const FILE_DESCRIPTOR_SET: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/wfe_descriptor.bin"));