Make hostapd WpaEventHandler available to upper layers

[abeltrano]

Type

• Bug fix
• Feature addition
• Feature update
• Documentation
• Build Infrastructure

Side Effects

• Breaking change
• Non-functional change

Goals

• Allow the middleware layers to access the hostapd event handler/producer.

Technical Details

• Add IHostapd::GetEventHandler exposing a shared_ptr<WpaEventHandler> associated with the instance.
• Implement IHostapd::GetEventHandler in Hostapd.
• Convert std::unique_ptr<WpaEventHandler> to std::shared_ptr in Hostapd.

Test Results

• All unit tests pass.

Reviewer Focus

• None

Future Work

• Register a listener on the handler in the AccessPointControllerLinux implementation.

Checklist

• Build target all compiles cleanly.
• clang-format and clang-tidy deltas produced no new output.
• Newly added functions include doxygen-style comment block.