jest: support custom testEnvironment (#834) #1345

Job	Run time
Build and publish Knip	30s
Run (create-typescript-app, JoshuaKGoldberg/create-typescript-app, pnpm install pnpm dlx $PKG_URL )	23s
Run (slonik, gajus/slonik, pnpm install pnpm dlx $PKG_URL )	36s
Run (10ten-ja-reader, birchill/10ten-ja-reader, pnpm install pnpm dlx $PKG_URL )	38s
Run (DefinitelyTyped-tools, microsoft/DefinitelyTyped-tools, pnpm install pnpm dlx $PKG_URL )	46s
Run (query, TanStack/query, pnpm install pnpm add -D -w $PKG_URL pnpm test:knip --cache pnpm test...	1m 44s
Run (argos, argos-ci/argos, pnpm i -g pnpm pnpm install pnpm add -D -w $PKG_URL pnpm run knip --f...	53s
Run (eslint, eslint/eslint, npm install --force npm install --prefix docs npm install --force -D ...	1m 48s
Run (TypeScript, microsoft/TypeScript, npm ci npm install -D $PKG_URL npm run knip )	58s
Run (mocha, mochajs/mocha, npm ci npm install -D $PKG_URL npm run lint:knip )	35s
Run (InvokeAI, invoke-ai/InvokeAI, invokeai/frontend/web, cd invokeai/frontend/web pnpm install p...	1m 28s
Run (prettier, prettier/prettier, yarn yarn --cwd scripts/release yarn --cwd scripts/tools/bundle...	49s
Run (freeCodeCamp, freeCodeCamp/freeCodeCamp, pnpm i -g pnpm pnpm install cp sample.env .env pnpm...	1m 20s
	12m 28s

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