Add method and subpath flags to timetrigger object for triggering a function (#3017)

* Update timetrigger crd and add method and subpath fields in spec.
Update fission-cli to accept user input for method and subpath fields.
Update publisher package to utilize these fields for triggering a function.
Update timer controller to use method and subpath fields for publishing a request.
Add a new test TestPublisherSubpath in pulisher package.

Signed-off-by: Md Soharab Ansari <soharab.ansari@infracloud.io>

* Use kubebuilder default annotation.
Update test for fission-cli timetrigger create, update command to support method and subpath flags.

Signed-off-by: Md Soharab Ansari <soharab.ansari@infracloud.io>

---------

Signed-off-by: Md Soharab Ansari <soharab.ansari@infracloud.io>

pkg/publisher/publisher.go

@@ -25,6 +25,6 @@ type (
 		// Publish a request to a "target". Target's meaning depends on the
 		// publisher: it's a URL in the case of a webhook publisher, or a queue
 		// name in a queue-based publisher such as NATS.
-		Publish(ctx context.Context, body string, headers map[string]string, target string)
+		Publish(ctx context.Context, body string, headers map[string]string, method, target string)
 	}
 )