Add handling for the identity packet to be split across two messages.
Summary: If the identity packet is split across two packets, then save it until we get a notification that more data is available for reading over the bluetooth link.
Test Plan: Connect a phone and laptop over Bluetooth, and verify that both the phone and laptop are able to see each other, and that either side can start and successfully go through the pairing process.
Reviewers: KDE Connect, mtijink
Reviewed By: KDE Connect, mtijink
Subscribers: mtijink, kdeconnect
Tags: KDE Connect
Differential Revision: https://phabricator.kde.org/D17789