Add shop validation

[gonzaloriestra]

Description

https://docs.google.com/document/d/1c0iXhKBpm-yhvff0iSgq1XwBSPL39fTBVajIJ3svaxU/edit?usp=sharing

Checklist:

• My commit message follow the pattern described in here
• I have performed a self-review of my own code.
• I have added tests that prove my fix is effective or that my feature works.
• I have updated the project documentation.
• I have added a changelog line.

[zzooeeyy]

There's also a similar sanitize method from shopify_app gem, I wonder if the logic can be extracted so we don't have to maintain 2 packages for validating Shopify URLS

[gonzaloriestra]

I've finally copied the code from there. Once we release a new version, we could use it from shopify_app, as it's already using shopify-api-ruby. Makes sense?

[lizkenyon]

I would prefer we don't remove this in this PR. But rather log a warning that this will be remove in a future version. i.e we should deprecate now remove later.

This will allow us to group our breaking changes together.

  ShopifyAPI::Logger.deprecated(
    "The `shop` parameter for `exchange_token` is deprecated and will be removed in v17. " \
    "The shop is now always taken from the session token's `dest` claim.",
    "17.0.0"
  )

[gonzaloriestra]

Oh, sorry, I misread your previous comment. Updated!