[CoreInternal] Add async flush method #3557

Job	Run time
catalyst	7m 2s
spm-package-resolved	1m 0s
pod-lib-lint (ios, macos-14, Xcode_15.2)	12m 42s
pod-lib-lint (ios, macos-14, Xcode_16)	13m 12s
pod-lib-lint (tvos, macos-14, Xcode_15.2)	7m 58s
pod-lib-lint (tvos, macos-14, Xcode_16)	6m 9s
pod-lib-lint (macos --skip-tests, macos-14, Xcode_15.2)	2m 22s
pod-lib-lint (macos --skip-tests, macos-14, Xcode_16)	2m 24s
pod-lib-lint (watchos, macos-14, Xcode_15.2)	2m 45s
pod-lib-lint (watchos, macos-14, Xcode_16)	1m 54s
spm (macos-13, Xcode_15.2, iOS)	6m 53s
spm (macos-14, Xcode_15.4, iOS)	6m 6s
spm (macos-15, Xcode_16, iOS)	2m 16s
spm (macos-15, Xcode_16, tvOS)	2m 1s
spm (macos-15, Xcode_16, macOS)	1m 59s
spm (macos-15, Xcode_16, watchOS)	2m 1s
spm (macos-15, Xcode_16, catalyst)	2m 13s
spm (macos-15, Xcode_16, visionOS)	3m 25s
core-cron-only	0s
	1h 24m 22s

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