Support for browser tester

[Joery-M]

Act version

0.2.61

Feature description

Some testing libraries are able to use browsers when running tests.

It would be nice to be able to use either a browser from the host machine.

In my case I use Vitest with it's, albeit experimental, browser runner to test a webassembly library, and when using act, Vitest just waits indefinitely for a browser to launch.

Actions on GitHub seem to include a browser in their containers when running tests, maybe act can copy this.