[Backport #16458] Add missing showInStore attributes

[aschrammel]

Description

This PR as a backport for #16458

Add missing showInStore attributes on Braintree configuration as there are some values that are changeable on store view (title, descriptors, merchant name override) and are not accessible from store view level due to the missing store view level permission for the containing group.

Braintree configuration offers the possibility to change following fields on store view level:

• Basic Braintree Settings => Title
• PayPal through Braintree => Title
• PayPal through Braintree => Override Merchant Name
• Dynamic Descriptors => Name
• Dynamic Descriptors => Phone
• Dynamic Descriptors => URL

All the fields are correctly shown in default config and on website level, but when changing to storeview, nothing is shown at all when expanding Braintree section.

Fixed Issues (if relevant)

Manual testing scenarios

1. Go to Stores => Configuration => Sales => Payment Methods
2. Click "Configure" next to "Braintree" under "Recommended Solutions"
3. All groups are shown
4. Switch from "Default Config" to a random Store View
5. Repeat step 2 - no groups are shown

After applying the PR, the above mentioned fields in their respective groups are shown.

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)

Original PR

#16458

[magento-engcom-team]

Hi @sidolov, thank you for the review.
ENGCOM-2189 has been created to process this Pull Request

[magento-engcom-team]

Hi @orlangur, thank you for the review.
ENGCOM-2189 has been created to process this Pull Request

[magento-engcom-team]

Hi @aschrammel. Thank you for your contribution.
We will aim to release these changes as part of 2.1.15.
Please check the release notes for final confirmation.