fix: webpack-uni-mp-loader should support nested node_modules

[yangyuanxx]

When webpack-uni-mp-loader call restoreNodeModules to restore the modulePath, it should support nested node_modules folder structure. e.g:

mp-alipay
|-- node-modules <-- first one
  |-- npm-scope-ali
    |-- ui-uniapp
      |-- node-modules <-- another nested one
        |-- @ali
          |-- primitive-uniapp

Before fixed:

restoreNodeModules returns: "node_modules/@ali/ui-uniapp/node-modules/@ali/primitive-uniapp"
(ATTENTION to the second node-modules, it should be node_modules)

After fixed:

restoreNodeModules returns: "node_modules/@ali/ui-uniapp/node_modules/@ali/primitive-uniapp"
(ATTENTION to the second node_modules, it is correct now)