AddToCart config entity
Config Interface for all configs
Abstract command
Interface for new commands
Add new add to cart command and update product command to extend from AbstractCommand
Add new command. Ideally this class should load all commands in this package which implement CommandInterface. Probably should be seperate factories for each command
Fix docblocks and add typehinting
Abstract Service
Add product to cart
Service Interface
Update to use abstract class and interface
Add docblocks
Add newline to err message