WebDriver: Missing endpoints

[AtkinsSJ]

This is a revival of https://github.com/SerenityOS/serenity/issues/15551, with the already-implemented endpoints stripped out.

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WebDriver is the API for remote-controlling a browser process, as used by WebPlatformTests. It has a lot of different endpoints, so to make it clear which ones are missing, here's a handy list!

To add an endpoint you'll need to modify the code in three places:

• The library definitions at Userland/Libraries/LibWeb/WebDriver.
• The WebDriver side at Userland/Services/WebDriver.
• The Browser side at Userland/Services/WebContent/WebDriver.

Comment here or refer to this issue in your PR to get your endpoints checked off the list. :^)

You can find the same table in the spec at https://w3c.github.io/webdriver/#endpoints

• [x] POST /session/{session id}/frame Switch To Frame

  1403

• [x] POST /session/{session id}/frame/parent Switch To Parent Frame

  1412

• [x] POST /session/{session id}/element/{element id}/clear Element Clear

  1727

• [x] POST /session/{session id}/element/{element id}/value Element Send Keys

  1725

• [x] POST /session/{session id}/actions Perform Actions

  1566

  1706

• [x] DELETE /session/{session id}/actions Release Actions

  1566

Additionally, some endpoints are partially implemented with FIXMEs in Userland/Services/WebContent/WebDriverConnection.cpp which need resolving before WebDriver will work completely.

[hanpham32]

I can work on implementing some of FIXMEs in Userland/Services/WebContent/WebDriverConnection.cpp if no one has been working on this yet

[trflynn89]

All endpoints are implemented.