refactor(@angular/build): define an internal ngHmrMode value #1391

Job	Run time
build	18s
lint	2m 21s
e2e_windows (windows-2025, 22, npm, 3)	38s
e2e_windows (windows-2025, 22, npm, 1)	35s
e2e_windows (windows-2025, 22, npm, 2)	2m 20s
e2e_windows (windows-2025, 22, npm, 0)	47s
e2e_windows (windows-2025, 22, esbuild, 0)	1m 9s
e2e_windows (windows-2025, 22, esbuild, 5)	52s
e2e_windows (windows-2025, 22, esbuild, 1)	41s
e2e_windows (windows-2025, 22, npm, 5)	44s
e2e_windows (windows-2025, 22, esbuild, 2)	38s
e2e_windows (windows-2025, 22, esbuild, 4)	35s
e2e_windows (windows-2025, 22, npm, 4)	1m 17s
e2e_windows (windows-2025, 22, esbuild, 3)	48s
publish-snapshots	0s
test	0s
Browser Compatibility Tests	0s
e2e-package-managers	0s
e2e-snapshots	0s
e2e	0s
	13m 43s

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