[LE Audio] New logic to generate the QR code

Currently the QR code string is generated in SettingsLib, and use
"<" and ">" to format the string.

Because the formatted string are multi layer nested, like
A:<B:<C:<<>;D:<>>;>;E:<F:<B:>;>;>;
Using Regex cannot handle this case,
- Regex cannot tell which B: is label for filed, which B: is user input
- Regex cannot tell which pair of <> is the correct open and close for B
- And these is no easy fix

The BluetoothLeBroadcastMetadata already implements the Parcelable
interface, use Parcel to serialize the string to fix issues.

Also, add unit test.

Fix: 248409874
Test: Unit test
Change-Id: I31ce4bb4f5e639deb0cb60ebd7d6bf904ae85788