Check order exists in wc_clear_cart_after_payment()

Fixes #6649
move $cart_updated inside $passed_validation IF statement. #6703
MX states Closes #6684 Fixes #6656
String sanitize_user Closes #6667
API - Variation handling for stock data

Closes #6626 cc @claudiosmweb
Incorrect variable

#6626 cc @claudiosmweb
When bulk editing variable products, set the stock status for non-stock managed variations

Fixes #6661
Fix coupons by date queries to prevent inflated results

Closes #6742
[2.2] During refunds, correctly set shipping tax totals

Fixes #6691
API - set_fee should support tax_data

Closes #6719 cc @maxrice
WooConf is over
[2.2] Ensure float is safely converted to string
Introduced 'woocommerce_find_rates' filter.
Introduced 'woocommerce_ajax_calc_line_taxes' filter.
[2.2] remove_taxes needs to clear line_tax_data
[2.2] If order_item_type is not set, don't query it in reports class
[2.2] Don't force tax_rate_id to an integer. Allow strings.

Used in Taxamo extension.
Allow plugins to filter the taxable location.

Ported over from 2.3 master branch.
Readme for 2.2.9
wc_prices_include_tax does not exist in 2.2