chore: make impl_handler macro self-contained #1658

Job	Run time
Lint	1m 28s
Test (windows-latest, x86_64-pc-windows-msvc)	5m 23s
Test (namespace-profile-mac-default, aarch64-apple-darwin)	58s
Test (ubuntu-latest, x86_64-unknown-linux-gnu)	2m 29s
Run task	4m 21s
CLI E2E test (ubuntu-latest)	4m 4s
CLI E2E test (namespace-profile-mac-default)	1m 46s
vite install E2E test	-1s
done	4s
	20m 32s

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