gh-137586: Open external osascript program with absolute path (GH-137584)

Open web browser with absolute path

On macOS, web browsers are opened via popen calling osascript. However,
if a user has a colliding osascript executable earlier in their PATH,
this may fail or cause unwanted behaviour.

Depending on one's environment or level of paranoia, this may be considered a security vulnerability.

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>