Plugins: Introduce plugin package specific logger (#62204)

* refactor

* implement with infra log for now

* undo moving

* update package name

* update name

* fix tests

* update pretty signature

* update naming

* simplify

* fix typo

* delete comment

* fix import

* retrigger

pkg/plugins/backendplugin/backendplugin.go

@@ -2,7 +2,7 @@
 package backendplugin
 
 import (
-	"github.com/grafana/grafana/pkg/infra/log"
+	"github.com/grafana/grafana/pkg/plugins/log"
 )
 
 // PluginFactoryFunc is a function type for creating a Plugin.