Add headless mode for firefox and edge

What does this MR do and why?

What:

1. Add headless mode for firefox and edge.
2. Fix acceptinsecurecerts error for firefox.
   Why:
3. The headless mode is not working for firefox and edge
4. There are Invalid moz:firefoxOptions field acceptInsecureCerts for firefox currently

Add headless mode for firefox and edge

changes:

1. Add headless mode for firefox and edge
2. Fix firefox acceptInsecureCerts error

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Goto qa directory and shell add ENV variables QA_BROWSER

   # for firefox 
   QA_BROWSER=firefox WEBDRIVER_HEADLESS=1 bundle exec bin/qa Test::Instance::All <test instance>-- -e 'Verify Pipeline API defined variable inheritance is determined based on forward:pipeline_variables condition'
   # for edge 
   QA_BROWSER=edge WEBDRIVER_HEADLESS=1 bundle exec bin/qa Test::Instance::All <test instance>-- -e 'Verify Pipeline API defined variable inheritance is determined based on forward:pipeline_variables condition'

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

/cc @daveliu