add .editorconfig file #55

Job	Run time
Swift 6 Language Mode	0s
Integration test / Windows (6.0)	4s
Soundness / API breakage check	52s
Integration test / Windows (nightly-6.0)	1s
Integration test / Windows (nightly-main)	1s
Integration test / Linux (5.9)	1m 34s
Soundness / Documentation check	1m 2s
Integration test / Linux (5.10)	1m 37s
Soundness / License headers check	4s
Integration test / Linux (6.0)	1m 55s
Soundness / Unacceptable language check	5s
Integration test / Linux (nightly-6.0)	2m 6s
Soundness / Broken symlinks check	3s
Soundness / Format check	35s
Soundness / Python lint check	6s
Integration test / Linux (nightly-main)	31s
Soundness / Shell check	33s
Soundness / YAML lint check	2s
Unit tests / Unit tests / Linux (5.9)	50s
Unit tests / Unit tests / Linux (5.10)	47s
Unit tests / Unit tests / Linux (6.0)	56s
Unit tests / Unit tests / Linux (nightly-6.0)	1m 1s
Unit tests / Unit tests / Windows (6.0)	2s
Unit tests / Unit tests / Linux (nightly-main)	30s
Unit tests / Unit tests / Windows (nightly-6.0)	3s
Unit tests / Unit tests / Windows (nightly-main)	3s
	15m 23s

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