[feature] Add a request ID and include it in logs (#1476)

This adds a lightweight form of tracing to GTS. Each incoming request is
assigned a Request ID which we then pass on and log in all our log
lines. Any function that gets called downstream from an HTTP handler
should now emit a requestID=value pair whenever it logs something.

Co-authored-by: kim <grufwub@gmail.com>

docs/configuration/observability.md

@@ -0,0 +1,16 @@
+# Observability
+
+These settings let you tune and configure certain observability related behaviours.
+
+## Settings
+
+```yaml
+##################################
+##### OBSERVABILITY SETTINGS #####
+##################################
+
+# String. Header name to use to extract a request or trace ID from. Typically set by a
+# loadbalancer or proxy.
+# Default: "X-Request-Id"
+request-id-header: "X-Request-Id"
+```