Add local browser Selenium tests for Blink(Chrome) and Webkit(Safari) about pdf2htmlex

[stephengaito]

Use the following dirvers:

1. firefox-geckodriver
2. snap chromium (includes driver)
3. webkit2gtk-driver and epiphany-browser -- may not work in selenium see
   below

See: https://www.selenium.dev/downloads/ (Platforms Supported by Selenium)
See: https://www.selenium.dev/selenium-ide/docs/en/plugins/plugins-getting-started/

Can NOT run chromium (as a snap) from inside a docker instance

Consider registering for saucelabs opensauce and use remote testing

Consider installation of tools required to run tests outside of docker

Conclusion: Resurrecting Lu Wang's "test_remote_browser" test tool and
using Sauce Lab's OpenSauce would provide much better testing with less
additional effort.