Add essential stalled / ending-too-soon debugging utilities. #108

Job	Run time
Lint	11s
Tests (addon-location)	15s
Tests (declarations-configuration)	27s
Tests (rollup-build)	14s
Slow tests: typescript with pnpm	13s
Tests (addon-only)	14s
Tests (monorepo with pnpm)	13s
Slow tests: typescript with npm	12s
Slow tests: try-scenarios	1m 28s
Slow tests: defaults with npm	1m 27s
Tests (test-app-location)	13s
Tests (monorepo with npm)	16s
Slow tests: defaults with pnpm	33s
	5m 56s

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