fix: do not destroy thread in UI thread

[zcbenz]

Description of Change

Destroying a thread implies joining it, and it should not be done in UI thread, otherwise it would cause assertions when DCHECK is enabled:

Backtrace:
        base::debug::CollectStackTrace [0x00007FF7C18D2172+18] (o:\base\debug\stack_trace_win.cc:284)
        base::debug::StackTrace::StackTrace [0x00007FF7C182A872+18] (o:\base\debug\stack_trace.cc:203)
        logging::LogMessage::~LogMessage [0x00007FF7C183DFF7+215] (o:\base\logging.cc:605)
        logging::LogMessage::~LogMessage [0x00007FF7C183ED40+16] (o:\base\logging.cc:598)
        base::internal::AssertBaseSyncPrimitivesAllowed [0x00007FF7C18A3DB6+214] (o:\base\threading\thread_restrictions.cc:165)
        base::internal::ScopedBlockingCallWithBaseSyncPrimitives::ScopedBlockingCallWithBaseSyncPrimitives [0x00007FF7C189F1FE+158] (o:\base\threading\scoped_blocking_call.cc:67)
        base::PlatformThread::Join [0x00007FF7C18E39DA+314] (o:\base\threading\platform_thread_win.cc:313)
        base::Thread::Stop [0x00007FF7C18A1190+128] (o:\base\threading\thread.cc:252)
        base::Thread::~Thread [0x00007FF7C18A10A7+23] (o:\base\threading\thread.cc:129)
        base::Thread::~Thread [0x00007FF7C18A2210+16] (o:\base\threading\thread.cc:127)
        base::TaskAnnotator::RunTask [0x00007FF7C188520F+431] (o:\base\task\common\task_annotator.cc:142)

The dialog module on Windows uses this behavior and crashes when used with DCHECK enabled.

This PR refactors the code to use ThreadPool to manage the threads to avoid allocating and destroying threads in UI thread, which follows the pattern used by BaseShellDialogImpl in Chromium. (We can not use BaseShellDialogImpl directly because it implies modal dialog with a parent.)

Checklist

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

Release Notes

Notes: none

[deepak1556]

LGTM 👍

[release-clerk]

No Release Notes

[trop]

I was unable to backport this PR to "8-x-y" cleanly;
you will need to perform this backport manually.

[trop]

I was unable to backport this PR to "7-2-x" cleanly;
you will need to perform this backport manually.

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I have automatically backported this PR to "9-x-y", please check out #23535

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@zcbenz has manually backported this PR to "8-x-y", please check out #23550

[trop]

@zcbenz has manually backported this PR to "7-2-x", please check out #23551