Fix: handle dependencies with package 'link' fields (#2690)

fix: when parsing dependencies, overwrite any 'link' property already set in package.json

Some projects, like Mozilla Aframe, set a 'link' property at the root of their package.json file.
This causes problems for our packageDependencies job, which extends that object and adds 'link'
to signify the dependency dir is a symlink. Overwrite property by default.

Closes #2685

packages/electron-builder-lib/src/util/packageDependencies.ts

@@ -208,6 +208,9 @@ class Collector {
     }
     else {
       metadata.parent = parent
+
+      // overwrite if already set by project package.json
+      metadata.link = undefined
     }
 
     metadata.path = rawDir