fix: add naming convention rule

[MaferMazu]

Description

This PR adds principally a rule for the naming convention prefix check in the phpcs.xml:

<rule ref="WordPress.NamingConventions.PrefixAllGlobals">
	<properties>
		<property name="prefixes" type="array" value="openedx_commerce" />
	</properties>
</rule>

Following the best practice for naming: https://developer.wordpress.org/plugins/plugin-basics/best-practices/#avoid-naming-collisions

The rest of the changes are adapting the namespace to that format.

Testing instructions

This is already uploaded in our stage WordPress installation. You can check if nothing breaks.
Credentials

Additional information

Error from WordPress.org:

Generic function/class/define/namespace/option names

All plugins must have unique function names, namespaces, defines, class and option names. This prevents your plugin from conflicting with other plugins or themes. We need you to update your plugin to use more unique and distinct names.

A good way to do this is with a prefix. For example, if your plugin is called "Easy Custom Post Types" then you could use names like these:
function ecpt_save_post()
define( 'ECPT_LICENSE', true );
class ECPT_Admin{}
namespace ECPT;
update_option( 'ecpt_settings', $settings );

Don't try to use two (2) or three (3) letter prefixes anymore. We host nearly 100-thousand plugins on WordPress.org alone. There are tens of thousands more outside our servers. Believe us, you’re going to run into conflicts.

You also need to avoid the use of __ (double underscores), wp_ , or _ (single underscore) as a prefix. Those are reserved for WordPress itself. You can use them inside your classes, but not as stand-alone function.

Please remember, if you're using _n() or __() for translation, that's fine. We're only talking about functions you've created for your plugin, not the core functions from WordPress. In fact, those core features are why you need to not use those prefixes in your own plugin! You don't want to break WordPress for your users.

Related to this, using if (!function_exists('NAME')) { around all your functions and classes sounds like a great idea until you realize the fatal flaw. If something else has a function with the same name and their code loads first, your plugin will break. Using if-exists should be reserved for shared libraries only.

Remember: Good prefix names are unique and distinct to your plugin. This will help you and the next person in debugging, as well as prevent conflicts.

Analysis result:
This plugin is using the prefix "openedxcommerce" for 7 element(s).
This plugin is using the prefix "openedx" for 8 element(s).

Looks like there are elements not using common prefixes.
openedx-commerce/openedx-commerce.php:41 function activate_openedx_commerce_plugin
openedx-commerce/openedx-commerce.php:50 function deactivate_openedx_commerce_plugin
openedx-commerce/openedx-commerce.php:58 function create_enrollment_logs_table
openedx-commerce/openedx-commerce.php:107 function run_openedx_commerce_plugin

When the report said that we use openedxcommerce in 7 elements as a prefix, it refers to the namespaces. The openedx in 8 elements is for the openedx_commerce in some function names, and it is taking only the first part.

Checklist for Merge

• Tested in a remote environment
• Updated documentation
• Rebased master/main
• Squashed commits

[openedx-webhooks]

Thanks for the pull request, @MaferMazu! Please note that it may take us up to several weeks or months to complete a review and merge your PR.

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[felipemontoya]

This looks great @MaferMazu, the tests are passing with the new check so I believe this is ready to merge.

[openedx-webhooks]

@MaferMazu 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.