AppBridge : Add the host param to the billing redirect url (gnikyt#1244)

Usage Charge "ID on Null" Fix (gnikyt#1210)

Verify shopify with SPA (gnikyt#1173)

* update config, add spa variable

* Continue if app already installed and has access token and not deleted

* disable cdn app bridge if spa used

* update verify

* add util helper

* update validation

* add frontend engine enum

* update frontend validation

* add frontend_engine config setting

* linter fix

* add tests

* simplified verification

* Fixes issue comparing enum for `useNativeAppBridge` utility method

* Changes test to ensure all tests use app config over Config::set for consistency

* Changes test to ensure all tests use app config over Config::set for consistency

* Changes enum/config setup for app bridge configuration to be string based

* Fixes to solve undefined magic method for frontend engine

Co-authored-by: Tyler King <tyler@osiset.com>

Verify shopify with SPA (gnikyt#1173)

* update config, add spa variable

* Continue if app already installed and has access token and not deleted

* disable cdn app bridge if spa used

* update verify

* add util helper

* update validation

* add frontend engine enum

* update frontend validation

* add frontend_engine config setting

* linter fix

* add tests

* simplified verification

* Fixes issue comparing enum for `useNativeAppBridge` utility method

* Changes test to ensure all tests use app config over Config::set for consistency

* Changes test to ensure all tests use app config over Config::set for consistency

* Changes enum/config setup for app bridge configuration to be string based

* Fixes to solve undefined magic method for frontend engine

Co-authored-by: Tyler King <tyler@osiset.com>

Simplify the auth flow by removing the full page redirect. (gnikyt#1075)

* Simplify the auth flow by removing the full page redirect.

🐛 Retain host parameter after successful install (gnikyt#900)

* 🐛 Retain host parameter after successful install

* Include host parameter in default view for appbridge 2.0

* Style violation

Co-authored-by: Stephen Sweetland <stephen@projectlambda.com>

Minor adjustments to formatting source.

StyleCI fixes

Updated CONTRIBUTORS.txt