Preserve overrides from root package

NPM 8.3.0 introduced the `overrides` key in package.json, which
allows you to customize the dependencies of any (or all) of your
project's dependencies. hydrate should respect the root project's
overrides.

src/actions/autoinstall/get-root-params.js

@@ -0,0 +1,16 @@
+let { existsSync, readFileSync } = require('fs')
+let { join } = require('path')
+
+// Get params from root project that should be preserved in hydrated package.json
+module.exports = function getRootParams ({ inv }) {
+  let root = inv._project.cwd
+  let packageJson = join(root, 'package.json')
+
+  let package = existsSync(packageJson) && JSON.parse(readFileSync(packageJson)) || {}
+
+  let result = {}
+  if (package.overrides)
+    result.overrides = package.overrides
+
+  return result
+}

src/actions/autoinstall/index.js

@@ -1,6 +1,7 @@
 let { existsSync, renameSync, writeFileSync } = require('fs')
 let { join } = require('path')
 let getRootDeps = require('./get-root-deps')
+let getRootParams = require('./get-root-params')
 let getSharedDeps = require('./get-shared-deps')
 let getLambdaDeps = require('./get-lambda-deps')
 
@@ -73,7 +74,8 @@ module.exports = function autoinstaller (params) {
         dir,
         file: 'package.json',
         remove: [ 'package.json', 'package-lock.json' ], // Identify files for later removal
-        data: JSON.stringify(lambdaPackage, null, 2)
+        data: JSON.stringify(lambdaPackage, null, 2),
+        ...getRootParams(inventory)
       }
       // Autoinstall can be called on a directory that contains a package.json with `"type": "module"` (and no dependencies)
       // If we find such a case, kindly move the existing package.json aside until autoinstall ops are complete