Convert `sync_back.py` to TypeScript #7138

Job	Run time
Go: tracing with autobuilder step (ubuntu-latest, stable-v2.19.4)	1m 28s
Go: tracing with autobuilder step (macos-latest, stable-v2.19.4)	5m 9s
Go: tracing with autobuilder step (ubuntu-latest, stable-v2.18.4)	1m 22s
Go: tracing with autobuilder step (ubuntu-latest, stable-v2.17.6)	1m 21s
Go: tracing with autobuilder step (macos-latest, stable-v2.17.6)	6m 6s
Go: tracing with autobuilder step (macos-latest, stable-v2.20.7)	5m 16s
Go: tracing with autobuilder step (ubuntu-latest, default)	1m 28s
Go: tracing with autobuilder step (macos-latest, stable-v2.18.4)	5m 14s
Go: tracing with autobuilder step (macos-latest, default)	4m 42s
Go: tracing with autobuilder step (macos-latest, linked)	4m 29s
Go: tracing with autobuilder step (ubuntu-latest, stable-v2.22.4)	1m 23s
Go: tracing with autobuilder step (macos-latest, nightly-latest)	5m 16s
Go: tracing with autobuilder step (ubuntu-latest, stable-v2.20.7)	1m 24s
Go: tracing with autobuilder step (macos-latest, stable-v2.22.4)	5m 49s
Go: tracing with autobuilder step (macos-latest, stable-v2.21.4)	6m 10s
Go: tracing with autobuilder step (ubuntu-latest, nightly-latest)	1m 15s
Go: tracing with autobuilder step (ubuntu-latest, linked)	1m 9s
Go: tracing with autobuilder step (ubuntu-latest, stable-v2.21.4)	1m 23s
	1h 0m 24s

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