add a tab to display test result

This MR adds a tab to display the test result that was done in the past.

The tab contains a button, once clicked, it will look for old test result jsons and dump it into the tables and graphs in the GUI page.

By default, it will show you the latest test result. User can also select to display a particular test result with a specified tag, either from a dropdown menu (menu items are designed for powerboard QC steps at LBNL), or manually enter a custom tag in a text box (custom tag will overwrite the dropdown menu).

In the testing tab, the user can now also set a tag for a test by entering a custom in a text box or select from the dropdown menu (custom tag will overwrite the dropdown menu).

The testing tab and display test result tab can be used at the same time if needed (just need to open them in two separate browser tabs)