Restore Reviews into a new Extension moved from contrib to solidusio

[fthobe]

The current review extension does not function on the new front-end and comes with very outdated code. Considering the discussions made in the following two issues it was decided to make a hard fork into a new extension as the burden of maintenance seems to have reached the limit of what's possible.
#63
#120

Planed Features

The new extension will contain following features:

• Endpoints and starter frontend integration to allow users / customers to leave a review on a 5 star scale (1-5) and a comment with the review and an approval process;
• Integration on the PDP of the starter frontend
• Integration on the taxon pages inside the product cards
• Endpoints to allow users / customers to upvote or downvote a review (thumbs up / thumbs down) reflected also in the frontend with the possibility to toggle the entire feature or negative votes on and off;
• An Endpoint to report a review;
• A Management Interface to approve or disapprove reviews;
• New Columns in the admin interface to show upvotes / downvotes
• A verification if the user is a "Verified Review" and has purchased the product before;
• The model of reviews will also be extended to include the store id allowing at a later point to return reviews only on the matching store considering also multi store environments in addition to multi-language environments through the local;
• A method of configuration to allow toggling the feature on store fronts in a multistore environment

Future Features

• Integration with the new frontend

Dropped Features

1. The legacy Front-End will not be supported
2. All endpoints allowing users to review reviews (no, they are there, it's not a pun), will be fully removed

What will be responsibility of the operator of the store

While the feature will allow moderation in either offensive (approve reviews before publication) or defensive (disapprove published reviews) manor, bot and spam protection will be left to the operator of the store. Suggestions will be given in the readme.md.

Features that are nice to have

• Add positive/negative review endpoint #63 allowing to sort for better reviews by using the thumbs up / down functionality

[fthobe]

@tvdeyen @jarednorman

Questions:

1. is cache counting and a table an acceptable way to count the thumbs up thumbs down actions? It is outlined in a guide in the edge documetation as a reference implementation to count likes
2. Do you have other preferences or no gos?