[Forwardport] of PR-#11707 to 2.3-develop UPS Option to include TAX in rate

[gwharton]

Description

The current UPS Module uses the UPS Rate excluding TAX to use as the rate charged to the customer during checkout.

This modification adds an additional config option so you can choose whether to request and include TAX information from UPS in the rate or not.

This modification is especially useful for businesses who are not TAX registered and cannot claim back the TAX charged by UPS. This allows them to pass on the TAX costs to the customer as part of the overall shipping rate.

Fixed Issues (if relevant)

N/A

Manual testing scenarios

Unit tests provided to cover code changes

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)