refactor(@angular-devkit/schematics): add explicit return types to fu… #1530

Job	Run time
build	11s
lint	2m 7s
e2e_windows (windows-2025, 22, npm, 1)	44s
e2e_windows (windows-2025, 22, npm, 2)	37s
e2e_windows (windows-2025, 22, esbuild, 1)	35s
e2e_windows (windows-2025, 22, esbuild, 0)	1m 7s
e2e_windows (windows-2025, 22, esbuild, 2)	42s
e2e_windows (windows-2025, 22, npm, 3)	37s
e2e_windows (windows-2025, 22, npm, 5)	1m 44s
e2e_windows (windows-2025, 22, npm, 4)	37s
e2e_windows (windows-2025, 22, npm, 0)	44s
e2e_windows (windows-2025, 22, esbuild, 5)	1m 44s
e2e_windows (windows-2025, 22, esbuild, 4)	37s
e2e_windows (windows-2025, 22, esbuild, 3)	24s
test	-1s
Browser Compatibility Tests	-1s
publish-snapshots	-1s
e2e	0s
e2e-snapshots	0s
e2e-package-managers	0s
	12m 27s

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