Add `.editorconfig` syntax highlighting #690

Job	Run time
build (windows-latest, Release)	13s
build (windows-latest, Debug)	13s
build (ubuntu-latest, Debug)	16s
build (macos-latest, Debug)	28s
build (macos-latest, Release)	16s
build (ubuntu-latest, Release)	14s
build (windows-latest, Release)	13s
build (macos-latest, Debug)	29s
build (ubuntu-latest, Release)	15s
build (windows-latest, Debug)	13s
build (ubuntu-latest, Debug)	14s
build (macos-latest, Release)	33s
build (ubuntu-latest, Debug)	14s
build (macos-latest, Debug)	29s
build (windows-latest, Release)	13s
build (windows-latest, Debug)	13s
build (ubuntu-latest, Release)	13s
build (macos-latest, Release)	17s
	5m 16s

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