Add support for emrun --browser to point to a macOS browser app root path (#26928)

The convention taken for `EMTEST_BROWSER` is to have it point to the
macOS app, and not the path to the executable inside the app. Fix emrun
to also use this same convention.

Fixes test `emrun.test_emrun` on macOS, when
`EMTEST_BROWSER=/Applications/Safari.app`

http://clbri.com:8010/api/v2/logs/434413/raw_inline

Author: juj

emrun.py

@@ -1609,6 +1609,10 @@ def run(args):  # noqa: C901, PLR0912, PLR0915
 
   options = emrun_options = parse_args(args)
 
+  if MACOS and options.browser.endswith('.app') and not options.browser.startswith('open'):
+    options.browser_args = f'--new --fresh --background -a {options.browser} {options.browser_args}'
+    options.browser = 'open'
+
   if options.android_tunnel:
     options.android = True