Plugins: Refactor cleaning of call resource response headers (#67145)

First part of #66889 moving cleaning of call resource response headers 
within plugin management client.

pkg/services/pluginsintegration/clientmiddleware/utils.go

@@ -0,0 +1,11 @@
+package clientmiddleware
+
+import (
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+)
+
+type callResourceResponseSenderFunc func(res *backend.CallResourceResponse) error
+
+func (fn callResourceResponseSenderFunc) Send(res *backend.CallResourceResponse) error {
+	return fn(res)
+}