* Abstract WP plugin code into a PluginsHelper class
We plan to use these methods in the Marketing tab.
* Add PluginsHelper::is_plugin_active()
* Add PluginsHelper::is_plugin_installed()
* Add PluginsHelper::get_plugin_data()
* Add PluginsHelper::get_plugin_path_from_slug()
* Refactor PluginsHelper::get_plugin_data method
Using the new get_plugin_path_from_slug method
* Refactor is_plugin_installed and is_plugin_active
Also adds support for plugin slugs or paths as parameters.
* Ensure get_plugins() function is available for PluginsHelper
* Ensure plugin path is a string before checking if installed/active
* PHPCS fixes
* Add initial unit tests for PluginsHelper
* Check plugin data array keys rather than all values
Will make it less fragile when Woo plugin data changes
* Fix typos
Co-authored-by: Daniel Bitzer <danielbitzer@gmail.com>
Jason Conroy