Add option for launching Pipewire inside the VM to serve Bluetooth
endpoints, which can be used in tests.

Make the option to optionally take path to the audio daemon, so e.g.
Pulseaudio support can be added later.

Tests running inside the VM don't need access to sound cards running on
the host.

This reverts commit 91a48af52efb0751fab396b2b9026c9186b10b88
This reverts commit e20e7e0b05c7edb74255c9b092916ac5bb99c97f

This rework config option parsing adding helper function to make it
simpler to parse new options.

This uses the btd_profile.experimental to mark the driver as
experimental.

This adds experimental field to btd_adapter_driver so the plugin can
indicate drivers that depends on experimental to be enabled.

If plugin .init returns -ENOTSUP treat it as the system doesn't
support the driver since that is the error returned by
btd_profile_register when experimental is disabled.

This uses the btd_profile.experimental to mark the driver as
experimental.

This uses the btd_profile.experimental to mark the driver as
experimental.

This uses the btd_profile.experimental to mark the driver as
experimental.

This uses the btd_profile.experimental to mark the driver as
experimental.