fix: properly fire serial-port-added and serial-port-removed events

[jkleinsc]

Description of Change

Closes #34887.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: fixed serial-port-added and serial-port-removed events not firing.

[codebytere]

It look like the tests themselves pass but then in the dtor there's a crash:

Received signal 11 <unknown> 000000000000
0   Electron Framework                  0x0000000123eb0952 base::debug::CollectStackTrace(void**, unsigned long) + 18
1   Electron Framework                  0x0000000123dcd413 base::debug::StackTrace::StackTrace() + 19
2   Electron Framework                  0x0000000123eb08a1 base::debug::(anonymous namespace)::StackDumpSignalHandler(int, __siginfo*, void*) + 1345
3   libsystem_platform.dylib            0x00007ff803414dfd _sigtramp + 29
4   Electron Framework                  0x0000000125dbcb25 mojo::core::ports::Node::AcceptEvent(mojo::core::ports::NodeName const&, std::Cr::unique_ptr<mojo::core::ports::Event, std::Cr::default_delete<mojo::core::ports::Event>>) + 2277
5   Electron Framework                  0x0000000123e22b21 base::ScopedValidateSequenceChecker::ScopedValidateSequenceChecker(base::SequenceCheckerImpl const&) + 33
6   Electron Framework                  0x0000000123df0e97 base::internal::WeakReference::IsValid() const + 39
7   Electron Framework                  0x000000011f3e6dc8 base::ObserverList<content::SerialDelegate::Observer, false, true, base::internal::CheckedObserverAdapter>::RemoveObserver(content::SerialDelegate::Observer const*) + 104
8   Electron Framework                  0x000000011f3e90d7 electron::SerialChooserController::~SerialChooserController() + 327
9   Electron Framework                  0x000000011f3e566c electron::ElectronSerialDelegate::~ElectronSerialDelegate() + 124
10  Electron Framework                  0x000000011f37dbce electron::ElectronBrowserClient::~ElectronBrowserClient() + 190
11  Electron Framework                  0x000000011f37dc6e electron::ElectronBrowserClient::~ElectronBrowserClient() + 14
12  Electron Framework                  0x000000011f27c850 ElectronMain + 192
13  dyld                                0x000000010966651e start + 462
[end of stack trace]
✗ Electron tests failed with kill signal SIGSEGV.

[jkleinsc]

The crash was resolved by following an approach similar to: [webhid] Notify chooser context observers on shutdown.

[jkleinsc]

Merging as CI failure is known CI issue unrelated to this PR.

[release-clerk]

Release Notes Persisted

fixed serial-port-added and serial-port-removed events not firing.

[trop]

I was unable to backport this PR to "17-x-y" cleanly;
you will need to perform this backport manually.

[trop]

I was unable to backport this PR to "18-x-y" cleanly;
you will need to perform this backport manually.

[trop]

I was unable to backport this PR to "19-x-y" cleanly;
you will need to perform this backport manually.

[trop]

I have automatically backported this PR to "20-x-y", please check out #35047