Fix binary view event ownership

[tinysec]

Summary

• expose official BinaryViewType lifecycle event registration helpers
• use explicit Cdecl callbacks with process-lifetime rooting
• pass independently referenced BinaryView objects to managed callbacks
• catch callback exceptions before they cross the native boundary
• preserve Core.RegisterBinaryViewEvent as a compatibility forwarder

Verification

• dotnet build BinaryNinja.csproj --no-restore
• targeted real-core BinaryViewEventTests: 1/1 passed
• full external real-core E2E: 257/257 passed