[action logs] Add action log plugin library class

[laoneo]

Summary of Changes

As extension dev, I like to do as less repetitive work as possible. This pr adds a base class extension devs can use to log actions more convenient. For example a plugin can then look like:

JLoader::import('com_actionlogs.libraries.actionlogplugin', JPATH_ADMINISTRATOR . '/components');

class PlgActionlogFoo extends ActionLogPlugin
{
	public function onContentAfterSave($context, $item, $isNew)
	{
		if ($context != 'com_foo.bar')
		{
			return;
		}

		$message = array(
			'action'   => $isNew ? 'add' : 'update',
			'type'     => 'PLG_ACTIONLOG_FOO_TYPE_BAR',
			'id'       => $item->id,
			'title'    => $item->title,
			'itemlink' => 'index.php?option=com_foo&task=edit&id=' . $item->id
		);

		$this->addLog(array($message), 'PLG_ACTIONLOG_FOO_' . $message['action'], $context);
	}
}

Additionally it simplifies the default Joomla log plugin.

Testing Instructions

Save an article.

Expected result

An action log is created.

Actual result

An action log is created.

Documentation Changes Required

Document that a base class exists.

[mbabker]

Use JLoader::register() the same way that is done for the privacy plugins please.

[mbabker]

Should be /** @var ... for IDEs to correctly pick up this inline doc block. Otherwise it's just seen as a "normal" comment.

[laoneo]

In PHPStorm it works also with one *. But I will change it. There are more places to cleanup then.

[laoneo]

Done the changes.

[ciar4n]

I have tested this item ✅ successfully on d48be2f

Action log created after save

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/22389.}

[infograf768]

I have tested this item ✅ successfully on d48be2f

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/22389.}

[infograf768]

RTC.

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/22389.}

[infograf768]

Note:
The plugin uses the list() method which can be confusing depending on the php version.