chore: Add duplicate package checker plugin

[ptbrowne]

Outputs warnings if libraries are multiple times in a bundle.

For example in contacts.

    WARNING in hoist-non-react-statics
      Multiple versions of hoist-non-react-statics found:
        2.5.5 ./~/cozy-client/~/hoist-non-react-statics
        3.3.0 ./~/hoist-non-react-statics
    
    
    WARNING in lodash
      Multiple versions of lodash found:
        4.17.13 ./~/cozy-device-helper/~/lodash
        4.17.14 ./~/cozy-client/~/lodash
        4.17.15 ./~/lodash
    
    
    WARNING in prop-types
      Multiple versions of prop-types found:
        15.6.2 ./~/cozy-client/~/prop-types
        15.7.2 ./~/prop-types
    
    
    WARNING in react
      Multiple versions of react found:
        16.7.0 ./~/cozy-client/~/react
        16.8.6 /Users/cozy/code/cozy/create-cozy-app/packages/cozy-scripts/~/react
    
    
    WARNING in regenerator-runtime
      Multiple versions of regenerator-runtime found:
        0.10.5 ./~/babel-polyfill/~/regenerator-runtime
        0.11.1 ./~/babel-runtime/~/regenerator-runtime
        0.13.2 ./~/@babel/runtime/~/regenerator-runtime
    
    
    WARNING in unist-util-visit-parents
      Multiple versions of unist-util-visit-parents found:
        1.1.2 ./~/unist-util-visit-parents
        2.1.2 ./~/unist-util-visit/~/unist-util-visit-parents
    
    
    WARNING in warning
      Multiple versions of warning found:
        3.0.0 ./~/warning
        4.0.3 ./~/node-polyglot/~/warning

Useful to detect libraries that are too strict in their package.json (mostly ours).

[drazik]

LGTM

[y-lohse]

Awesome! (the feature, not the duplication in contacts)

[drazik]

Looks like some snapshots are failing now :s

[ptbrowne]

The tests are not passing even on master on my machine (issue here #1283 ). Issue here, since this is not urgent, I will not investigate right now on this issue.