Disable hardware-wallets on platforms that don't support `libusb` (#8464)

* disable hardware-wallets that don't support libusb

* address grumbles

* nits

* Refactor to get rid off as much annotations asap

* Might consume slight more memory than pure conditional compilation
flags

* formatting nits

* Enable libusb for android

* Tested by it compiling succesfully with `cargo build --target=armv7--linux-androideabi`
* The binary is ~66 MB

```bash
$ size
size target/armv7-linux-androideabi/release/parity
text    	data     	bss     	dec     	hex 		filename
50676230        416200   	31456 		51123886        30c16ae 	target/armv7-linux-androideabi/release/parity
```

* Move all `fake-hardware-wallet` to its own crate

* Removes some conditional compilation flags
* Introduces `fake-hardware-wallet` crate

* return error if no hardware wallets are found