feat: add vertical stack variant to horizontal navigation item #6191

Job	Run time
Verify (packages/styles)	52s
Verify (packages/tokens)	52s
Verify (packages/placeholders)	49s
Verify (packages/docs)	7m 57s
Verify (packages/components)	2m 39s
Verify (packages/eslint-plugin)	1m 56s
Verify (packages/theming)	47s
Verify Chromatic	1m 50s
	17m 42s

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