Add the ability to run in sandbox mode

[jcblw]

Description

Before this, there was an assumption that all usage of this action would be ran un the --no-sandbox flag. This is not recommended by the Puppeteer team. This implements creating a user and allowing that user access to all the resources needed to run the test.

closes #17

[jcblw]

Running into issues getting the new sandboxed user access to the workflow directory.

See mujo-code/source/runs/276297037

[jcblw]

@stefanbuck or @bantic if y'all have any ideas to get around this I'm all ears 😁

[stefanbuck]

I'm sorry for the very late reply. Somehow this message slipped through my inbox. I don't see any issue with adding such a user.