Reorganize file util functionality (#7848)

* reorganize file util functionality

* fix api test compilation

* fix rebase issue

einterfaces/brand.go

@@ -12,13 +12,3 @@ type BrandInterface interface {
 	SaveBrandImage(*multipart.FileHeader) *model.AppError
 	GetBrandImage() ([]byte, *model.AppError)
 }
-
-var theBrandInterface BrandInterface
-
-func RegisterBrandInterface(newInterface BrandInterface) {
-	theBrandInterface = newInterface
-}
-
-func GetBrandInterface() BrandInterface {
-	return theBrandInterface
-}

einterfaces/elasticsearch.go

@@ -18,13 +18,3 @@ type ElasticsearchInterface interface {
 	PurgeIndexes() *model.AppError
 	DataRetentionDeleteIndexes(cutoff time.Time) *model.AppError
 }
-
-var theElasticsearchInterface ElasticsearchInterface
-
-func RegisterElasticsearchInterface(newInterface ElasticsearchInterface) {
-	theElasticsearchInterface = newInterface
-}
-
-func GetElasticsearchInterface() ElasticsearchInterface {
-	return theElasticsearchInterface
-}

einterfaces/emoji.go

@@ -10,13 +10,3 @@ import (
 type EmojiInterface interface {
 	CanUserCreateEmoji(string, []*model.TeamMember) bool
 }
-
-var theEmojiInterface EmojiInterface
-
-func RegisterEmojiInterface(newInterface EmojiInterface) {
-	theEmojiInterface = newInterface
-}
-
-func GetEmojiInterface() EmojiInterface {
-	return theEmojiInterface
-}