Change set_console_mode() to use greenthreads

This method now uses a worker thread to set the console mode asynchronously
similarly to several other methods.

Followup patch to changes Ia707766855bd7ec47a5af05e119b126504ddc0b1 and
Ie03afd66d365e48c9dc3dc48f31e93a08e07e79f.

Co-Authored-By: Michael Davies <michael@the-davies.net>

Change-Id: I96d4214ba86f2b1d489b5120c379adfca28a0a7d
Partial-Bug: #1285507