Add RPCErrorConvertible #88

Job	Run time
Soundness / Check generated code	1m 16s
Soundness / Swift license headers check	5s
Cxx interop / Construct Cxx interop matrix	3s
Benchmarks / Construct Benchmarks matrix	3s
Unit tests / Construct unit test matrix	3s
Examples / Linux (5.9)	26s
Examples / Linux (5.10)	26s
Examples / Windows (6.0)	2s
Examples / Linux (6.0)	5m 45s
Examples / Windows (nightly-6.0)	2s
Examples / Windows (nightly-main)	3s
Soundness / API breakage check	1m 5s
Examples / Linux (nightly-6.0)	7m 14s
Soundness / Broken symlinks check	5s
Examples / Linux (nightly-main)	3m 12s
Soundness / Documentation check	1m 17s
Soundness / Format check	35s
Soundness / Shell check	32s
Soundness / License headers check	3s
Soundness / Unacceptable language check	3s
Soundness / Python lint check	9s
Soundness / YAML lint check	9s
Benchmarks / Benchmarks / Linux (6.0)	2m 39s
Benchmarks / Benchmarks / Linux (nightly-6.0)	3m 23s
Benchmarks / Benchmarks / Linux (nightly-main)	5m 16s
Cxx interop / Cxx interop / Linux (6.0)	1m 2s
Cxx interop / Cxx interop / Linux (nightly-6.0)	1m 9s
Cxx interop / Cxx interop / Linux (nightly-main)	10m 45s
Unit tests / Unit tests / Linux (6.0)	1m 20s
Unit tests / Unit tests / Linux (nightly-6.0)	1m 38s
Unit tests / Unit tests / Linux (nightly-main)	1m 45s
	51m 35s

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