Placeholder functions
Setters + wc_create_order + wc_update_order for #4169
Set correct post type
woocommerce_order_add_fee
static WC_Tax class - no need for a constructor in this
When setting totals, if not set get the data from the product
Also use qty
Fire action when adding product
Calculate tax and totals methods
Tax class fixes + notices
Cleaned up ajax tax calc function
Notices
Use a transaction during checkout's order creation method to ensure all data gets set

Closes #5368
Merge branch 'feature-wc-create-order'