Use `which()` to get Firefox path on Mac OS (#10818)
Use `which()` to get Firefox path on Mac OS (#10818)

The Firefox binary under Mac OS was using a hardcoded path. This was
failing when trying to manipulate PATH env var to use firefox from a
different location or if Firefox was installed in a different place.

Fixes #10686

Co-authored-by: Simon K <d7e6eefb81c9889acea80ad6121985bae0d61209@gmail.com>
Co-authored-by: Diego Molina <bb22cf37947d84e3dd6d6c3568ebe68e7d79c52d@users.noreply.github.com>
valfirst/selenium,SeleniumHQ/selenium,joshmgrant/selenium,SeleniumHQ/selenium,valfirst/selenium,titusfortner/selenium,HtmlUnit/selenium,HtmlUnit/selenium,joshmgrant/selenium,joshmgrant/selenium,valfirst/selenium,joshmgrant/selenium,SeleniumHQ/selenium,SeleniumHQ/selenium,valfirst/selenium,HtmlUnit/selenium,titusfortner/selenium,joshmgrant/selenium,SeleniumHQ/selenium,SeleniumHQ/selenium,titusfortner/selenium,valfirst/selenium,joshmgrant/selenium,SeleniumHQ/selenium,valfirst/selenium,titusfortner/selenium,titusfortner/selenium,titusfortner/selenium,titusfortner/selenium,titusfortner/selenium,SeleniumHQ/selenium,HtmlUnit/selenium,joshmgrant/selenium,joshmgrant/selenium,HtmlUnit/selenium,valfirst/selenium,HtmlUnit/selenium,valfirst/selenium,valfirst/selenium,SeleniumHQ/selenium,valfirst/selenium,HtmlUnit/selenium,HtmlUnit/selenium,SeleniumHQ/selenium,SeleniumHQ/selenium,joshmgrant/selenium,joshmgrant/selenium,valfirst/selenium,titusfortner/selenium,HtmlUnit/selenium,HtmlUnit/selenium,titusfortner/selenium,titusfortner/selenium,joshmgrant/selenium