[MM-28422] Enable processing of import files through API (#16062)

* Implement unzip function

* Implement FileSize method

* Implement path rewriting for bulk import

* Small improvements

* Add ImportSettings to config

* Implement ListImports API endpoint

* Enable uploading import files

* Implement import process job

* Add missing license headers

* Address reviews

* Make path sanitization a bit smarter

* Clean path before calculating Dir

* [MM-30008] Add mmctl support for file imports (#16301)

* Add mmctl support for import files

* Improve test

* Remove unnecessary handlers

* Use th.TestForSystemAdminAndLocal

* Make nouser id a constant

store/sqlstore/upload_session_store.go

@@ -93,9 +93,6 @@ func (us SqlUploadSessionStore) Get(id string) (*model.UploadSession, error) {
 }
 
 func (us SqlUploadSessionStore) GetForUser(userId string) ([]*model.UploadSession, error) {
-	if !model.IsValidId(userId) {
-		return nil, errors.New("SqlUploadSessionStore.GetForUser: userId is not valid")
-	}
 	query := us.getQueryBuilder().
 		Select("*").
 		From("UploadSessions").