Add 'ENABLE_LE_ENHANCED_CONNECTION_COMPLETE_EVENT' for BtStack examples

[bittailor]

This fixes an issue for the picow_bt_example_sm_pairing_peripheral example when a central, that removed its bonding information, does a re-bonding to previously bonded peripheral that still has the bonding information stored.

1. Connect with a central (like nRFConnect app on a phone) to the picow_bt_example_sm_pairing_peripheral peripheral.
2. Do a bondning
3. Disconnect from peripheral
4. Delete the bonding information on the central
5. Connect again to the same peripheral
6. Again do a bonding

Without the change in this PR step 6 fails on the peripheral with

Pairing failed, authentication failure with reason = 11

and the peripheral disconnects.

With the changes in the PR step 6 succeeds and a bonded connection is established.

For more details see this google groups discussion with @mringwal

[mringwal]

@peterharperuk The CYW43 supports this feature and it fixes the issue that @bittailor did run into.

We also have released BTstack v1.8 which only seems to require a single file name change (hids_client.c to hids_host.c) in the CMakeLists.txt.