How do you include a field.tpl.php, to a custom views field handler. outside of the theme?
If you want to have a template file being loaded from your module's templates folder, you should do the following:


Implement hook_views_api to tell Views where you keep views templates, e.g. your_module/templates
Following the naming conventions for Views and add views-view-field.tpl.php into your module's template folder, e.g. your_module/templates


After you clear your cache and rescan the template folders using Views UI, your tpl file should be selected.

Hope this helps, the main source for this answer was https://stevenyeung.com/article/template-override-drupal-views-3-from-module/