fix #101 chose default camera, get more specific if position is wrong

[SigiNeumann]

#101
It seems on some iPhone (12/13), the picking order of captureDevices would provide suboptimal captureDevices e.g. DualWideCamera on iPhone12, where InWideAngleCamera would be better.
Instead of chosing a specific deviceType, we use the system default and only pick if position (front/back) is wrong. This becomes neccessary bc. of the overloads of getDefaultDevice

[SigiNeumann]

For reference I wanted to check how others are doing and it seems that ZXing did a similar change
Redth/ZXing.Net.Maui@76ef652

[afriscic]

There was a request a while back to support dual and triple cameras as they enable smoother zoom experience. Before that the code selected only wide camera.

If you experience problem with scanning on iPhones try to set small zoom factor.