Renaming in BluetoothTile and QSDetailItems

Rename the fields so they could disclose the type.

1. Rename icon to iconResId(type: int)
2. Rename iconDrawable to icon(type QSTile.Icon)
3. Rename BluetoothBatteryDrawable to BluetoothBatteryTileIcon

Bug: 68008183
Test: Build

Change-Id: I5edb24c2fcfa114c2d7134898d4e2b2bcedf0758