BLE Split Link Layer Improvements

[carlescufi]

This issue lists all the improvements we want to include that are not part of bringing the Split Link Layer up to parity with the existing one (#12681).

• Add support for Controller (SW deferred)-based Privacy (BLE controller: Add support for Controller(SW deferred)-based Privacy #14621)
• Change the role dependent event-done handling from type switch-case to callback concept.
• Move the LLL event prepare/resume queue/handling into LLL. (@cvinayak )
• Move the LLL-to-ULL Tx ack queue API to ULL domain.
• Add documentation for ticker @stko-ot
• Include the diagrams done by @pskhansen in the documentation
• Robustness fix (nice to have): bluetooth: controller: Check on done queue performed too late #13389
• Add tests in nrf52_bsim to run on upstream CI for (at least basic) controller functionality
• Style fixes (Failing LL.TS Data Length Update Tests (split) #22048)
• Create a porting guide to help users port to new radio hardware

[aescolar]

"- [ ] Use atomic_cas when supported by the arch without disabling interrupts (see for more info)"
was removed due to #13471 being closed

[aescolar]

"- [ ] Add support for (current) Mesh Extensions (#14678)"
removed as there was no real interest for that, and the ticket was morphed into adding full mesh extensions to the controller.

[cfriedt]

Ooooo - I like this! It might also be a good idea to add a basic / minimum recommendation and documentation for the radio API. Naturally, most chips will have a different radio, but we are mostly using the same interface so far. However, that interface is largely undocumented. Some state diagrams would be nice as well.

[carlescufi]

Ooooo - I like this! It might also be a good idea to add a basic / minimum recommendation and documentation for the radio API. Naturally, most chips will have a different radio, but we are mostly using the same interface so far. However, that interface is largely undocumented. Some state diagrams would be nice as well.

Just added a point at the end, thanks!

[joerchan]

Add tests in nrf52_bsim to run on upstream CI for (at least basic) controller functionality

Isn't this done?