Recently came across a strange issue where Dolphin would hard crash in most games with this error:
```sh
/usr/include/c++/15.2.1/optional:1165: constexpr const _Tp* std::optional<_Tp>::operator->() const [with _Tp = InputCommon::ImagePixelData]: Assertion 'this->_M_is_engaged()' failed.
```
The culprit turned out to be accessing `host_key_image` which is an `std::optional` thay may return `std::nullopt`. I'm not sure why this issue started occuring for me since I've had no issue with my Dynamic Input Textures in the past? But this fixes a crash if the image fails to load.
This lets us get rid of the Reset call in ProcessInputPayload, which was
causing us some threading headaches (see 74ed5e5532). Instead we handle
disconnection in the same way as the libusb implementation does.
We can register a BroadcastReceiver to have Android tell us when a GC
adapter gets connected instead of having a loop where we continuously
call SleepCurrentThread(1000) and poll the current status. When waiting
for a GC adapter to connect, this both reduces power usage and improves
responsiveness.
Note that I made openAdapter get the UsbDevice that's been stored by the
hotplug code instead of having openAdapter find the UsbDevice on its own
like before. This is only because I want to ensure that the UsbDevice
being tracked for disconnection is the same as the UsbDevice actually
being used, in case the user has multiple adapters connected.