MMCTL: Add import delete cmd for removing the import files (#29764)

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/channels/api4/import_local.go

@@ -7,4 +7,5 @@ import "net/http"
 
 func (api *API) InitImportLocal() {
 	api.BaseRoutes.Imports.Handle("", api.APILocal(listImports)).Methods(http.MethodGet)
+	api.BaseRoutes.Import.Handle("", api.APILocal(deleteImport)).Methods(http.MethodDelete)
 }