add .editorconfig file #25

Job	Run time
Unit tests / Linux (5.9 - jammy)	2m 54s
Unit tests / Windows (${{ matrix.swift_version }} - ${{ ((contains(matrix.swift_version, 'nightly') && 'windows-2019') \|\| 'windows-2022') }})	0s
Unit tests / Linux (5.10 - jammy)	2m 51s
Unit tests / Linux (6.0 - jammy)	3m 3s
Unit tests / Linux (nightly-main - jammy)	3m 26s
Unit tests / Linux (nightly-6.0 - jammy)	3m 32s
Soundness / API breakage check	2m 40s
Soundness / Documentation check	2m 6s
Soundness / License headers check	4s
Soundness / Unacceptable language check	4s
Soundness / Broken symlinks check	2s
Soundness / Format check	33s
Soundness / Shell check	33s
Soundness / Python lint check	10s
Soundness / YAML lint check	5s
	22m 3s

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