Screen remains off when folded

- [x] I have read the [FAQ](https://github.com/Genymobile/scrcpy/blob/master/FAQ.md).
- [x] I have searched in existing [issues](https://github.com/Genymobile/scrcpy/issues).

**Environment**
- OS: Windows 10 Pro
- scrcpy version: 1.17
- installation method: choco install scrcpy
- device model: Samsung Galaxy Z Flip (SM-F700F)
- Android version: 11 (One UI 3.0)

**Describe the bug**
I want to use scrcpy while my phone screen is folded/closed. However it seems unresponsive to any input from either `scrcpy` or `adb`, it just stays off or shows a fading image for a few seconds.
I've obviously tried RMB and all combinations of `--stay-awake` and `--turn-screen-off`. I've also tried sending all kinds of `adb` commands (mostly key inputs) to power the screen back on, to no avail. Also, all on/off combinations of auto-lock and always-on display. The result is always the same: screen is off or a still image of the always-on display.
I was able to control the little external screen targeting it with `--display` while the phone was folded, but that's it.

I know this is an edge case, but as folding phones rise in popularity (at least I hope so, I love the form factor of this one) I think using scrcpy would be a very useful way to avoid unnecessary mechanical wear.

Start by reproducing the behavior on a Samsung Galaxy Z Flip running Android 11 with scrcpy 1.17, comparing a folded device with the external display selected via --display. Check whether input sent by scrcpy or adb can wake or control the main screen while folded. Done means establishing whether folded-screen control can work and documenting or fixing the behavior, with the --display case as a comparison.

Written by the indexing model from the issue text.