add video dialog component for custom landing page (fixes #7175) (#7176) #562

Job	Run time
Preparing	8s
Pre-Planet build	0s
Deploy single language build	8m 7s
Planet build (amd64)	1m 13s
Planet build (arm)	1m 12s
Planet build (arm64)	1m 15s
Manifest build	19s
	12m 14s

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