Add Entitlement API Proxy

[mr-vara]

Proposed changes

This PR adds proxy API call to the Hiive API sites/v1/entitlements

The Rest API:
GET /newfold-data/v1/entitlements

Response:

{
    "solution": null,
    "entitlements": [],
    "categories": [],
    "solutions": [
        {
            "name": "Commerce",
            "sku": "SOLUTIONS_COMMERCE",
            "description": "Incidunt deleniti veritatis consectetur odio beatae dolores voluptatem. Temporibus eaque sunt aut consequuntur. Aut magni voluptatem minus temporibus distinctio et voluptatem.",
            "price": "22.92",
            "fullPrice": "35.08",
            "url": "http://www.schumm.info/quaerat-asperiores-velit-consequuntur-iure-sequi-aut-deleniti",
            "ctbId": null,
            "features": null
        },
        {
            "name": "Agency",
            "sku": "SOLUTIONS_SERVICE",
            "description": "Qui saepe et sunt dignissimos autem nam. Quo occaecati ea iste ducimus. Hic mollitia sequi rerum eum error. Quo at sed suscipit tempore qui sequi.",
            "price": "24.09",
            "fullPrice": "33.30",
            "url": "http://boyer.com/odit-nobis-ut-est",
            "ctbId": null,
            "features": null
        },
        {
            "name": "Creator",
            "sku": "SOLUTIONS_CONTENT",
            "description": "Consequatur accusantium incidunt quod aut earum vero. Velit rerum sit quibusdam eligendi esse placeat. Molestias aperiam doloremque quo id accusantium ut et sapiente. Ut neque fugiat dolores.",
            "price": "27.29",
            "fullPrice": "39.76",
            "url": "https://www.hegmann.com/maxime-odit-blanditiis-cumque-qui",
            "ctbId": null,
            "features": null
        }
    ]
}

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Video

Checklist

• I have read the CONTRIBUTING doc
• I have viewed my change in a web-browser
• Linting and tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[girish-lokapure]

have moved it to wp-module-solutions module.
newfold-labs/wp-module-solutions#2