bluetooth-client: Don't limit discovered devices to devices with Discoverable=true
Some low-end / budget bluetooth devices (keyboards, mice) don't get discovered properly when a Discoverable=true filter is set.
These do show up in bluetoothctl since bluetoothctl by default sets an empty filter. Do the same so that these devices get discovered properly.
2 examples of such devices are:
Device 09:02:01:03:0F:87 (public)
Name: Bluetooth 3.0 Keyboard
Alias: Bluetooth 3.0 Keyboard
Class: 0x00000540
Icon: input-keyboard
Paired: yes
Bonded: yes
Trusted: yes
Blocked: no
Connected: yes
WakeAllowed: yes
LegacyPairing: yes
UUID: Service Discovery Serve.. (00001000-0000-1000-8000-00805f9b34fb)
UUID: Human Interface Device... (00001124-0000-1000-8000-00805f9b34fb)
UUID: PnP Information (00001200-0000-1000-8000-00805f9b34fb)
Modalias: bluetooth:v05ACp022Cd011B
Device 00:60:D1:00:00:34 (public)
Name: Bluetooth Mouse
Alias: Bluetooth Mouse
Class: 0x00002580
Icon: input-mouse
Paired: yes
Bonded: yes
Trusted: yes
Blocked: no
Connected: yes
WakeAllowed: yes
LegacyPairing: no
UUID: Human Interface Device... (00001124-0000-1000-8000-00805f9b34fb)
UUID: PnP Information (00001200-0000-1000-8000-00805f9b34fb)
Modalias: usb:v0103p0204d001E