expose isDirect on Vuln type, not just in JSON outpput

lib/vuln.js

@@ -78,6 +78,12 @@ class Vuln {
     }
   }
 
+  get isDirect () {
+    const edgesIn = [...this.nodes.values()].flatMap(n => [...n.edgesIn])
+    const isDirect = edgesIn.some(e => e.from.isProjectRoot)
+    return isDirect
+  }
+
   testSpec (spec) {
     const specObj = npa(spec)
     if (!specObj.registry)
@@ -94,13 +100,10 @@ class Vuln {
   }
 
   toJSON () {
-    const edgesIn = [...this.nodes.values()].flatMap(n => [...n.edgesIn])
-    const isDirect = edgesIn.some(e => e.from.isProjectRoot)
-
     return {
       name: this.name,
       severity: this.severity,
-      isDirect,
+      isDirect: this.isDirect,
       // just loop over the advisories, since via is only Vuln objects,
       // and calculated advisories have all the info we need
       via: [...this.advisories].map(v => v.type === 'metavuln' ? v.dependency : {