Make EventLoopPromise conform to Equatable #258

Job	Run time
Soundness / API breakage check	2m 38s
Soundness / Broken symlinks check	4s
Soundness / Documentation check	2m 10s
Soundness / Format check	55s
Soundness / Shell check	9s
Soundness / License headers check	7s
Soundness / Unacceptable language check	4s
Swift 6 Language Mode / Swift 6 language mode	1m 1s
Integration Tests / Linux (5.8)	13m 10s
Integration Tests / Linux (5.9)	14m 41s
Integration Tests / Linux (5.10)	14m 7s
Integration Tests / Linux (nightly-6.0)	16m 59s
Integration Tests / Linux (nightly-main)	17m 40s
Benchmarks / Benchmarks / Linux (5.8)	2m 35s
Cxx interop / Cxx interop / Linux (5.8)	1m 5s
Benchmarks / Benchmarks / Linux (5.9)	3m 51s
Cxx interop / Cxx interop / Linux (5.9)	1m 9s
Benchmarks / Benchmarks / Linux (5.10)	3m 33s
Cxx interop / Cxx interop / Linux (5.10)	1m 7s
Benchmarks / Benchmarks / Linux (nightly-6.0)	4m 54s
Cxx interop / Cxx interop / Linux (nightly-6.0)	1m 49s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 44s
Benchmarks / Benchmarks / Linux (nightly-main)	4m 39s
Unit tests / Unit tests / Linux (5.8)	3m 19s
Unit tests / Unit tests / Linux (5.9)	3m 29s
Unit tests / Unit tests / Linux (5.10)	3m 22s
Unit tests / Unit tests / Linux (nightly-6.0)	4m 29s
Unit tests / Unit tests / Linux (nightly-main)	4m 19s
	2h 9m 9s

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