fix(arborist): handle link nodes in old lockfiles correctly

[nlf]

we were previously assuming that a node with no version property is a link, however in old lockfiles a link target is also in the inventory and has a version so this check does not catch all edge cases

closes #3628

[npm-robot]

no statistically significant performance changes detected

timing results

app-large	clean	lock-only	cache-only	cache-only peer-deps	modules-only	no-lock	no-cache	no-modules	no-clean	no-clean audit
npm@8	47.223 ±1.45	27.309 ±0.06	15.852 ±0.02	18.142 ±0.83	2.673 ±0.03	2.660 ±0.05	2.110 ±0.01	10.433 ±0.09	2.103 ±0.05	3.014 ±0.02
#4614	46.930 ±0.74	29.050 ±0.27	16.543 ±0.08	19.178 ±0.71	2.790 ±0.01	2.754 ±0.00	2.245 ±0.01	10.895 ±0.06	2.219 ±0.01	3.290 ±0.11

app-medium	clean	lock-only	cache-only	cache-only peer-deps	modules-only	no-lock	no-cache	no-modules	no-clean	no-clean audit
npm@8	33.117 ±0.41	20.981 ±0.16	11.691 ±0.10	12.557 ±0.10	2.348 ±0.04	2.448 ±0.04	2.168 ±0.01	7.743 ±0.11	1.987 ±0.03	2.692 ±0.06
#4614	35.637 ±0.06	22.204 ±0.06	12.484 ±0.17	13.544 ±0.10	2.558 ±0.02	2.545 ±0.02	2.288 ±0.03	8.225 ±0.05	2.125 ±0.03	2.937 ±0.06