Fix/issue 2562 - Add Retail Delivery Fee for Colorado

[iyut]

Description

Adding a function for custom surcharge ( retail delivery fee ) for Colorado state. This changes also introduce a new filter hook that the user can use to disable the custom surcharge addition.

Related issue(s)

Fixes #2562

Steps to reproduce & screenshots/GIFs

1. Add product to the cart.
2. Use any Colorado address for the shipping address.
3. The Retail Delivery Fee will be displayed as a free on the cart.

Checklist

• unit tests

• changelog.txt entry added
• readme.txt entry added

[bartech]

I suggest to create separate file that have custom fees, maybe even folder to store logic per each case in separate file (function) that will return fee data or false.
In main hooked method check if $custom_fees contain item with $customer->get_shipping_country() . ':" . $customer->get_shipping_state().

$custom_fees = array(
	'US:CO' => 'custom_function_name'
);

If matched include custom fee logic file and run custom_function_name to check if fee should be applied, if should be applied return fee data.

array(
	'value' => 0.27 // can be calculated
	'label' => __( 'Retail Delivery Fee', 'woocommerce_services' ),
);

If fee should not be applied return false.

[bartech]

We should check if all chosen methods wc_get_chosen_shipping_method_ids() are local_pickup, if anyone of them is not fee should be applied.

[bartech]

We have to check if Colorado state Sales or Use Tax is charged on the items (see if we already have those taxes applied) as usually when items are exempt from state Sales or Use Tax they are exempt from Retail Delivery Fee.