Improve error message when func invoke is run outside function directory (#3018)

* Improve error message f
or func invoke

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

* fix the linting error

---------

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

Author: RayyanSeliya

cmd/invoke.go

@@ -154,7 +154,7 @@ func runInvoke(cmd *cobra.Command, _ []string, newClient ClientFactory) (err err
 		return err
 	}
 	if !f.Initialized() {
-		return fn.NewErrNotInitialized(f.Root)
+		return fmt.Errorf("no function found in current directory.\nYou need to be inside a function directory to invoke it.\n\nTry this:\n  func create --language go myfunction    Create a new function\n  cd myfunction                          Go into the function directory\n  func invoke                            Now you can invoke it\n\nOr if you have an existing function:\n  cd path/to/your/function              Go to your function directory\n  func invoke                           Invoke the function")
 	}
 
 	// Client instance from env vars, flags, args and user prompts (if --confirm)