Support an external screen
Epic: https://source.puri.sm/Librem5/use-cases/issues/108, https://source.puri.sm/Librem5/use-cases/issues/67
Users will want to connect their phone to an external screen. It is also worth noting that some backers signed up for the option that includes a phone and an external monitor, so we absolutely must support this.
The phone will output display port data and we want to use this with an HDMI monitor. The work required is:
- convert display port to HDMI to get HDMI out
- get display port changes into mainline (more complex than HDMI)
- look at USB-C parts
- runtime switches
We also need to decide if we want to support the use of the touch LCD panel at the same time as the external screen or not.