[Backport] Added option to exclude discount amount from minimum order amount calculation

[ccasciotti]

Original pull request: #19136

Description

This PR adds option for store manager to include or exclude discount amount from minimum order amount calculation. Sometimes client wants to exclude discount amount from minimum order and want that only subtotal is used. The default option is set to "Yes" so Magento will use the current behavior.

Fixed Issues (if relevant)

none

Manual testing scenarios

1. Access backend
2. Go to Stores > Configuration > Sales > Sales > Minimum Order Amount
3. Leave "Yes" in "Include Discount Amount" field to test normal behavior.
4. Set "No" in "Include Discount Amount" field to test new behavior without discount.

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)

[magento-cicd2]

All committers have signed the CLA.

[ccasciotti]

@magento-engcom-team give me test instance

[magento-engcom-team]

Hi @ccasciotti. Thank you for your request. I'm working on Magento instance for you

[magento-engcom-team]

Hi @ccasciotti, here is your new Magento instance.
Admin access: http://ec2-34-228-235-121.compute-1.amazonaws.com/pr-18524//admin
Login: admin Password: 123123q

[ccasciotti]

@magento-engcom-team manual test was successful, please review code

[orlangur]

Nowadays all changes must be applied to 2.3-develop first (see https://devdocs.magento.com/guides/v2.3/contributor-guide/contributing.html#rules). Please prepare a new pull request, this one should be on hold until the latter is merged.

[ccasciotti]

Hi @orlangur,
I've ported the change request's commit of the merged #19136 PR here, you can review code and eventually unlock this PR for the 2.2-develop.

Thanks.

[magento-engcom-team]

Hi @sidolov, thank you for the review.
ENGCOM-3986 has been created to process this Pull Request

[ghost]

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