Fission meets OpenTelemetry (#2157)

* add opentracing section and otelCollectorEndpoint
* initialize OTLP exporter
* pkg/controller: changes for context propagation
* pkg/executor: changes for context propagation
* pkg/fetcher: changes for context propagation
* pkg/router: changes for context propagation
* pkg/storagesvc: changes for context propagation
* set no default value for otel collector endpoint
* update readme and add notes to charts
* move common code to pkg/utils/otel
* adding fn and env as attributes
* don't use otelhttp transport for websocket
* URL ignore with common filter UrlsToIgnore

Note: The web socket example does not work when using OTEL HTTP. Here is an issue related to that on open-telemetry/opentelemetry-js-contrib.

Signed-off-by: Gaurav Gahlot <gauravgahlot0107@gmail.com>
Co-authored-by: Sanket Sudake <sanketsudake@gmail.com>

pkg/executor/executor_test.go

@@ -173,7 +173,7 @@ func TestExecutor(t *testing.T) {
 
 	// create poolmgr
 	port := 9999
-	err = StartExecutor(logger, functionNs, "fission-builder", port)
+	err = StartExecutor(logger, functionNs, "fission-builder", port, true)
 	if err != nil {
 		log.Panicf("failed to start poolmgr: %v", err)
 	}