Add initial Copilot instructions #9720

Job	Run time
check-codeql-versions	50s
analyze-actions	57s
analyze-javascript (ubuntu-22.04)	3m 51s
analyze-javascript (ubuntu-24.04)	3m 49s
analyze-javascript (ubuntu-22.04, linked)	3m 56s
analyze-javascript (windows-2022)	6m 40s
analyze-javascript (macos-13, linked)	6m 8s
analyze-javascript (ubuntu-24.04, linked)	3m 59s
analyze-javascript (macos-13)	5m 48s
analyze-javascript (windows-2025, linked)	9m 58s
analyze-javascript (macos-14)	4m 58s
analyze-javascript (windows-2022, linked)	6m 11s
analyze-javascript (macos-14, linked)	5m 7s
analyze-javascript (windows-2025)	7m 15s
analyze-javascript (macos-15, linked)	4m 42s
analyze-javascript (macos-15)	6m 45s
	1h 20m 54s

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