Create Symfony 6.2 example app

[mclack]

Goal

To document BugSnag being used in a Symfony 6 app. Symfony 6.2 is the latest maintained version of Symfony, and we currently have no ^6.x examples.

Design

Followed the current Symfony integration guide along with the symfony50 example app.

Changeset

symfony62 added to the example directory.

Testing

Tested each route configured in DefaultController.php - each exception was reported to the BugSnag dashboard successfully.