Add forget() to "Get Devices" sample

[beaufortfrancois]

This PR updates both "Get Devices" web bluetooth samples with the new forget() method that is available behind the same feature as navigator.bluetooth.getDevices().

Live previews:

• https://beaufortfrancois.github.io/samples/web-bluetooth/index.html
• https://beaufortfrancois.github.io/samples/web-bluetooth/get-devices.html
• https://beaufortfrancois.github.io/samples/web-bluetooth/get-devices-async-await.html

It currently requires the experimental chrome://flags/#enable-web-bluetooth-new-permissions-backend in Chrome 101.

@reillyeon PTAL