Convert `sync_back.py` to TypeScript #7139

Job	Run time
Go: tracing with custom build steps (ubuntu-latest, stable-v2.18.4)	1m 12s
Go: tracing with custom build steps (macos-latest, stable-v2.17.6)	2m 35s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.22.4)	1m 7s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.17.6)	1m 7s
Go: tracing with custom build steps (macos-latest, default)	2m 0s
Go: tracing with custom build steps (macos-latest, stable-v2.18.4)	3m 17s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.20.7)	1m 13s
Go: tracing with custom build steps (macos-latest, stable-v2.19.4)	3m 2s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.21.4)	59s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.19.4)	1m 11s
Go: tracing with custom build steps (ubuntu-latest, default)	55s
Go: tracing with custom build steps (macos-latest, stable-v2.22.4)	2m 39s
Go: tracing with custom build steps (macos-latest, stable-v2.21.4)	2m 22s
Go: tracing with custom build steps (macos-latest, linked)	2m 0s
Go: tracing with custom build steps (ubuntu-latest, nightly-latest)	1m 0s
Go: tracing with custom build steps (macos-latest, nightly-latest)	2m 34s
Go: tracing with custom build steps (ubuntu-latest, linked)	1m 0s
Go: tracing with custom build steps (macos-latest, stable-v2.20.7)	2m 27s
	32m 40s

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