[MM-19711] - Get plugin configuration without removing secrets (#11928)

* Method GetUnsanitizedConfig() exposed to API (Plugin) interface and his implementations

* improvements with some suggestions

* Fix documentation (final period added)

Co-Authored-By: Ali Farooq <25732808+ali-farooq0@users.noreply.github.com>

* Added some test for Plugin.GetConfig and Plugin.GetUnsanitizedConfig

* Removed empty lines

plugin/plugintest/hooks.go

@@ -4,11 +4,16 @@
 
 package plugintest
 
-import http "net/http"
-import io "io"
-import mock "github.com/stretchr/testify/mock"
-import model "github.com/mattermost/mattermost-server/model"
-import plugin "github.com/mattermost/mattermost-server/plugin"
+import (
+	io "io"
+	http "net/http"
+
+	mock "github.com/stretchr/testify/mock"
+
+	model "github.com/mattermost/mattermost-server/model"
+
+	plugin "github.com/mattermost/mattermost-server/plugin"
+)
 
 // Hooks is an autogenerated mock type for the Hooks type
 type Hooks struct {