[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

model/job.go

@@ -22,6 +22,7 @@ const (
 	JOB_TYPE_EXPIRY_NOTIFY                  = "expiry_notify"
 	JOB_TYPE_PRODUCT_NOTICES                = "product_notices"
 	JOB_TYPE_ACTIVE_USERS                   = "active_users"
+	JOB_TYPE_IMPORT_PROCESS                 = "import_process"
 	JOB_TYPE_CLOUD                          = "cloud"
 
 	JOB_STATUS_PENDING          = "pending"
@@ -66,6 +67,7 @@ func (j *Job) IsValid() *AppError {
 	case JOB_TYPE_PRODUCT_NOTICES:
 	case JOB_TYPE_EXPIRY_NOTIFY:
 	case JOB_TYPE_ACTIVE_USERS:
+	case JOB_TYPE_IMPORT_PROCESS:
 	case JOB_TYPE_CLOUD:
 	default:
 		return NewAppError("Job.IsValid", "model.job.is_valid.type.app_error", nil, "id="+j.Id, http.StatusBadRequest)