Backport: Allow template duplication + concept of active templates #12977

Job	Run time
Core running from src / Core running from src / Linux	1m 59s
Core running from build / Core running from build / Linux	2m 10s
Core running from build / Core running from build / Windows	3m 55s
Core running from src / Core running from src / Windows	3m 47s
Core running from build / Core running from build / MacOS	1m 43s
Core running from src / Core running from src / MacOS	3m 26s
Gutenberg running from build / Gutenberg running from build / Linux	9m 4s
Gutenberg running from src / Gutenberg running from src / Linux	8m 25s
Gutenberg running from build / Gutenberg running from build / Windows	12m 35s
Gutenberg running from src / Gutenberg running from src / Windows	12m 33s
Gutenberg running from build / Gutenberg running from build / MacOS	8m 34s
Gutenberg running from src / Gutenberg running from src / MacOS	9m 43s
Slack Notifications	0s
Failed workflow tasks	0s
	1h 17m 54s

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