refactor(@angular/build): provide private factory API for internal co… #1720

Job	Run time
lint	2m 12s
build	16s
e2e_windows (windows-2025, 22, npm, 1)	20s
e2e_windows (windows-2025, 22, npm, 3)	30s
e2e_windows (windows-2025, 22, esbuild, 0)	25s
e2e_windows (windows-2025, 22, esbuild, 4)	28s
e2e_windows (windows-2025, 22, npm, 5)	31s
e2e_windows (windows-2025, 22, npm, 4)	28s
e2e_windows (windows-2025, 22, npm, 0)	22s
e2e_windows (windows-2025, 22, esbuild, 1)	22s
e2e_windows (windows-2025, 22, esbuild, 2)	30s
e2e_windows (windows-2025, 22, npm, 2)	31s
e2e_windows (windows-2025, 22, esbuild, 3)	34s
e2e_windows (windows-2025, 22, esbuild, 5)	34s
Browser Compatibility Tests	0s
test	-1s
publish-snapshots	-1s
e2e-package-managers	-1s
e2e-snapshots	-1s
e2e	-1s
	7m 58s

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