Editor: Make asset registration .asset.php optional for blocks #2364

Job	Run time
Core running from build / Core running from build / Linux	1m 58s
Core running from src / Core running from src / Linux	1m 49s
Core running from build / Core running from build / Windows	3m 16s
Core running from src / Core running from src / Windows	4m 12s
Core running from build / Core running from build / MacOS	3m 40s
Core running from src / Core running from src / MacOS	3m 1s
Gutenberg running from build / Gutenberg running from build / Linux	8m 19s
Gutenberg running from src / Gutenberg running from src / Linux	8m 11s
Gutenberg running from build / Gutenberg running from build / Windows	13m 8s
Gutenberg running from src / Gutenberg running from src / Windows	13m 22s
Gutenberg running from build / Gutenberg running from build / MacOS	20m 44s
Gutenberg running from src / Gutenberg running from src / MacOS	11m 56s
Leave WordPress Playground details	2s
Slack Notifications	0s
Failed workflow tasks	0s
	1h 33m 38s

Provide feedback