Add Bluetooth provider and track card UI improvements

[KhyatiSaini]

Track details screen card

• added track details card to display track details

  

Track card in the uploaded tracks screen improved

• added popup menu on track card
• navigating to the track details screen on tapping show details on popup menu

   

Added Bluetooth provider

Created Bluetooth Provider class so that the Bluetooth related functions become available to be different widgets

• [x] scan nearby Bluetooth devices and display them on the bluetoothDevicesScreen.dart
• [x] connect to the nearby Bluetooth device
• [x] discovering services of the connected device
• [x] read characteristics
• [x] write characteristics
• [x] subscribe to characteristics