[Audiosharing] When bt is off or unsupported, we show "Please connect a...

[Audiosharing] When bt is off or unsupported, we show "Please connect a device" dialog after camera scans a QR code

Bug: 308368124
Flag: com.android.settingslib.flags.enable_le_audio_qr_code_private_broadcast_sharing
Test: atest
Change-Id: I89697e25b57d67fa765f5ad593b72f6cdecda418