Move to shiki and stabilize dual themes support #23401

Job	Run time
Build: ubuntu-latest	1m 14s
Build: windows-latest	1m 56s
Lint	50s
Test: ubuntu-latest (node@18)	6m 27s
Test (Smoke): ubuntu-latest (node@18)	23m 25s
Test (E2E): ubuntu-latest (node@18.17.1)	5m 5s
Test: ubuntu-latest (node@20.5.1)	6m 50s
Test (Smoke): windows-latest (node@18)	8m 2s
Test: macos-14 (node@18)	5m 58s
Test (E2E): windows-latest (node@18.17.1)	7m 39s
Test: windows-latest (node@18.17.1)	9m 27s
	1h 16m 53s

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