Bluetooth: tester: Update to recent conn param related changes in BTP

This updates tester application to recent changes in BTP related
to Connection Parameters Update.
Connected event has been extended with connection parameters.
Connection Parameters Update command and event have beend added to
initiate and track current connection parameters.
Needed to automate qualification test GAP/CONN/CPUP/BV-06-C

Signed-off-by: Mariusz Skamra <mariusz.skamra@codecoup.pl>