Don't show "always use" when app can't be default

Each USB device can have one default handler. This app is launched when
the device is plugged in. A default handler automatically gets
permission to access the device when launched.

All other apps have to request the permission to access the USB device
via UsbManager.requestPermission. In the permission dialog there is an
option to make the app the default app for the device. Of course this
only makes sense if this app declares the right properties to be
auto-launched. Hence check this and only then show this options.

Also made the string in the dialogs easier to understand.

AccessoryFilter and DeviceFilter needed to be copied so I can access
them from system-ui. No code change in these classes.

Test: requested permissions from app that could by the default for the
      device and from an app that could not. Also tested "confirm" flow
      that is executed when the device is plugged in and a app that
      might be default is installed.
Bug: 67381583
Change-Id: I12eb7efed0ad107c70ae32433a5629108f252486