Allow usage of local eav-attribute-groups.xml file

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### Preconditions

1. Setup a custom module for the migration as recommended by Magento [here](https://devdocs.magento.com/guides/v2.3/migration/migration-tool-configure.html#migration-configure)

### Steps to reproduce

1. Setup a custom module for the migration
2. In your config.xml file, point `eav_attribute_groups_file` to a file in `/app/code/Vendor/Migration/etc/.../eav_attribute_groups.xml`
3. Run the migration
4. `bin/magento migrate:data app/code/Vendor/Migration/etc/.../config.xml `

### Expected result

1. The migration should run with the values from our own eav_attribute_groups.xml file

### Actual result

1. The migration tool tries loading the eav_attribute_groups.xml file from the root of the vendor/magento/data-migration-tool and it throws an error that the file isn't found.
2. `In Groups.php line 54:

Invalid groups filename: /var/www/html/vendor/magento/data-migration-tool/app/code/{vendor}/Migration/etc/opensource-to-opensource/1.7.0.2/eav-attribute-groups.xml`

### Additional notes

1. If you copy your `eav-attribute-groups.xml` into vendor/magento/data-migration-tool/...` it will work just fine
2. Ideally we should never be touching anything in the vendor directory and all customization and configuration should be done at the local module level
3. The `map file` does support using one in your local module directory
4. It would be great to have the same type of support for the `eav-attribute-groups.xml` file

Start at Groups.php line 54 and the migrate:data command using the custom module's config.xml; compare the existing local map-file behavior described in the issue. Done means the migration resolves eav_attribute_groups_file from the local module path and runs using that eav_attribute_groups.xml instead of requiring a copy under vendor/magento/data-migration-tool.

Written by the indexing model from the issue text.