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

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

server/channels/app/import.go

@@ -410,3 +410,15 @@ func (a *App) ListImports() ([]string, *model.AppError) {
 
 	return results, nil
 }
+
+func (a *App) DeleteImport(name string) *model.AppError {
+	filePath := filepath.Join(*a.Config().ImportSettings.Directory, name)
+
+	if ok, err := a.FileExists(filePath); err != nil {
+		return err
+	} else if !ok {
+		return nil
+	}
+
+	return a.RemoveFile(filePath)
+}

server/channels/app/import_test.go

@@ -679,3 +679,37 @@ func TestImportBulkImportWithAttachments(t *testing.T) {
 	files := GetAttachments(adminUser.Id, th, t)
 	require.Len(t, files, 11)
 }
+
+func TestDeleteImport(t *testing.T) {
+	th := Setup(t)
+	defer th.TearDown()
+
+	importDir := filepath.Join(th.tempWorkspace, "data", "import")
+	err := os.MkdirAll(importDir, os.ModePerm)
+	require.NoError(t, err)
+	f, err := os.Create(filepath.Join(importDir, "import.zip"))
+	require.NoError(t, err)
+	f.Close()
+	defer func() {
+		err = os.RemoveAll(importDir)
+		require.NoError(t, err)
+	}()
+
+	t.Run("delete import successful", func(t *testing.T) {
+		imports, err := th.App.ListImports()
+		require.Nil(t, err)
+		require.Equal(t, 1, len(imports))
+		require.Equal(t, "import.zip", imports[0])
+
+		delErr := th.App.DeleteImport("import.zip")
+		require.Nil(t, delErr)
+
+		imports, err = th.App.ListImports()
+		require.Nil(t, err)
+		require.Equal(t, 0, len(imports))
+
+		//idempotency check
+		delErr = th.App.DeleteImport("import.zip")
+		require.Nil(t, delErr)
+	})
+}