[MM-14576] Add GetBundlePath method to Plugin API (#10466)

* Fix typo

* Add GetBundlePath method to Plugin API

* Change signature to GetBundlePath() (string, error)

* Add test

plugin/api.go

@@ -44,7 +44,12 @@ type API interface {
 	// Minimum server version: 5.6
 	SavePluginConfig(config map[string]interface{}) *model.AppError
 
-	// GetLicense returns the current license used by the Mattermoset server. Returns nil if the
+	// GetBundlePath returns the absolute path where the plugin's bundle was unpacked.
+	//
+	// Minimum server version: 5.10
+	GetBundlePath() (string, error)
+
+	// GetLicense returns the current license used by the Mattermost server. Returns nil if the
 	// the server does not have a license.
 	//
 	// Minimum server version: 5.10