floss: Add on_device_connection_failed callback

Add a callback to immediately notify the browser that a pending
connection attempt failed.

Uprev btmanagerd version to 0.7.1,  this is backward compatible API change.

Bug: 353527430
Test: mmm packages/modules/Bluetooth
Flag: EXEMPT, Floss only change

Change-Id: I27cc51c76731c8d9113ad5bf025a14bec48d27ca