Fix for issue 38703 deselect default attr options

[rostilos]

Description (*)

The ability to remove the default options under Visual, Text Swatch and Dropdown attributes has been added ( a separate button under the list )

And also - for multiselect attribute ( being finalized )

Related Pull Requests

Fixed Issues (if relevant)

1. Fixes magento/magento2#38703

Manual testing scenarios (*)

1.Described in the original issue

Questions or comments

This is more as a suggested option, but I'd like to clarify implementation issues, perhaps the reviewers will suggest a better option

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)
• [ ] README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• [ ] All automated tests passed successfully (all builds are green)