GCS Colibri: add custom configuration page

This makes sure to only present valid options for the
gemini frame. It also validates the configuration.
Colibri: enable USB VSENSE pull up

This makes USB enumeration more reliable when using external
power.
Colibri: disable unused FreeRTOS functions

This is consistent with changes that happened with other
targets.
Colibri: switch to using pios_thread

Avoiding using FreeRTOS thread handling directly. This allows us
to swap out the RTOS backend easily.