Move populateSketchbookMenu to a separate thread #141

Job	Run time
Test Processing	1m 8s
(linux/aarch64) Create Processing Build	8m 38s
(linux/x64) Create Processing Build	8m 56s
(windows/x64) Create Processing Build	11m 0s
(macos/x64) Create Processing Build	5m 45s
(macos/aarch64) Create Processing Build	3m 18s
	38m 45s

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