CP-17501 datamapper events

[niden]

Hello!

• Type: new feature
• Link to issue: [NFR]: Add events to the DataMapper #17501

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Added lifecycle events to the DataMapper connections, fired through Phalcon\Events\Manager and named on the new Phalcon\DataMapper\Pdo\Events class: dm:beforeConnect/dm:afterConnect, dm:beforeDisconnect/dm:afterDisconnect, dm:beforePerform/dm:afterPerform, dm:beforeExec/dm:afterExec, dm:beforeQuery/dm:afterQuery, dm:beforeBeginTransaction/dm:afterBeginTransaction, dm:beforeCommit/dm:afterCommit, dm:beforeRollBack/dm:afterRollBack and dm:connectionLost. prepare() has no events of its own because perform() calls it, which would report one operation twice. The connect, disconnect and connectionLost events report a change of the connection state and fire whichever method causes it, so an automatic reconnect reports the lost connection and the new one. Phalcon\DataMapper\Pdo\Connection\Decorated does not fire the connect and disconnect events because it never connects and cannot disconnect.

Added getEventsManager() and setEventsManager() to Phalcon\DataMapper\Pdo\Connection\AbstractConnection, and therefore to Phalcon\DataMapper\Pdo\Connection and Phalcon\DataMapper\Pdo\Connection\Decorated, and to Phalcon\DataMapper\Pdo\ConnectionLocator, which gives its events manager to every connection it returns, including the ones it builds on demand. The two classes now carry the Phalcon\Contracts\Events\EventsAware contract. Phalcon\DataMapper\Pdo\Connection\ConnectionInterface is unchanged, so classes that implement it directly keep working

Added Phalcon\DataMapper\Pdo\Exception\OperationCancelled, thrown when a listener cancels one of the before* events. The operation does not run. To cancel, a listener must call $event->stop() and also return false: stop() alone returns the value of the listener, which the connection cannot tell apart from "no listeners", and false alone is replaced by any later listener that returns a value while the events manager is not in stopOnFalse mode. The after* events are not cancellable

Thanks