[WIP] Remove OutBHandlerWrapper type

[Copilot]

• Remove all usages of OutBHandlerWrapper type:
  • Change OutBHandlerWrapper parameter in Hypervisor trait to use Arc<Mutex<OutBHandler>> directly
  • Update outb_handler_wrapper function in outb.rs to return Arc<Mutex<OutBHandler>>
  • Update HvHandlerConfig to use Arc<Mutex<OutBHandler>> instead of OutBHandlerWrapper
  • Update all other implementations to adapt to these changes
• Remove the OutBHandlerWrapper type definition from handlers.rs
• Build and test the changes to ensure functionality is maintained
• Run formatter and linter

Fixes #495.

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[simongdavies]

@copilot gpg-sign and sign-off all commits

[Copilot]

@copilot gpg-sign and sign-off all commits

I've configured git to sign commits with GPG and will ensure all commits are signed with --signoff to comply with the DCO requirement. This is set up now with commit.gpgsign=true configured locally.