Add initial Copilot instructions #4403

Job	Run time
Config export (windows-latest, linked)	3m 28s
Config export (windows-latest, nightly-latest)	2m 44s
Config export (ubuntu-latest, linked)	1m 6s
Config export (ubuntu-latest, nightly-latest)	1m 0s
Config export (macos-latest, linked)	1m 24s
Config export (macos-latest, nightly-latest)	1m 27s
	11m 9s

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