Find client by handle during disconnect event.

[gkoh]

Rather than searching the client list by connection address, search by connection handle.
This avoids an issue where the target device has RPA enabled and addresses will not match.

Additionally, update the client peer address with the ID address when the identity has been resolved.

[gkoh]

This attempts to address #360.

I have only tested the getClientByHandle() change.

I have not tested the setPeerAddress() call after identity resolve, yet.

[gkoh]

This needs more thought.
I have just realised this half reverts the onConnectFail() fixes in 8cefc0a

[gkoh]

This PR went from half baked to totally unbaked 🙁
Upon testing the setPeerAddress() change, I got the very helpful:

E NimBLEClient: Cannot set peer address while connected

so, that isn't going to work either.

At this point, I think the right answer is to just add getClientByHandle() to the end of the search by addresses.
So:

• search by ota_addr
• search by id_addr
• search by conn_handle

[gkoh]

Updated to add search by connection handle after search by address fails.

[h2zero]

Awesome, thanks @gkoh