Show swiftc diagnostics with square brackets #442

Job	Run time
Test / Linux (5.8 - jammy)	3m 51s
Test / Windows (5.9 - windows-2022)	13m 10s
Test / Linux (5.9 - jammy)	4m 10s
Test / Windows (6.0 - windows-2022)	9m 6s
Test / Linux (5.10 - jammy)	8m 36s
Test / Linux (6.0 - jammy)	5m 19s
Soundness / API breakage check	0s
Soundness / Documentation check	0s
Soundness / Broken symlinks check	3s
Soundness / Format check	0s
Soundness / License headers check	0s
Soundness / Python lint check	9s
Soundness / Shell check	30s
Soundness / Unacceptable language check	3s
Soundness / YAML lint check	3s
	45m 0s

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