wasm: add puppeteer/playwright support for ghci browser mode

This commit adds support for using puppeteer/playwright for
automatically launching a headless browser that backs the ghci browser
mode. This is useful for testing the ghci browser mode as a part of
GHC testsuite, and it's also convenient for local development since
the step to start iserv can be automated away.

(cherry picked from commit fc576798)
(cherry picked from commit 760cb5f9)