Plugins: Unexport PluginDir field from PluginDTO (#59190)

* unexport pluginDir from dto

* more err checks

* tidy

* fix tests

* fix dboard file tests

* fix import

* fix tests

* apply PR feedback

* combine interfaces

* fix logs and clean up test

* filepath clean

* use fs.File

* rm explicit type

pkg/plugins/models.go

@@ -26,12 +26,11 @@ func (e NotFoundError) Error() string {
 }
 
 type DuplicateError struct {
-	PluginID          string
-	ExistingPluginDir string
+	PluginID string
 }
 
 func (e DuplicateError) Error() string {
-	return fmt.Sprintf("plugin with ID '%s' already exists in '%s'", e.PluginID, e.ExistingPluginDir)
+	return fmt.Sprintf("plugin with ID '%s' already exists", e.PluginID)
 }
 
 func (e DuplicateError) Is(err error) bool {
@@ -195,13 +194,10 @@ func (s SignatureType) IsValid() bool {
 	return false
 }
 
-type PluginFiles map[string]struct{}
-
 type Signature struct {
 	Status     SignatureStatus
 	Type       SignatureType
 	SigningOrg string
-	Files      PluginFiles
 }
 
 type PluginMetaDTO struct {