Logger for Sentry no longer active since PSR-3 introduction

[kdambekalns]

The settings in https://github.com/flownative/flow-sentry/blob/f655f0f735dcee0656073a0826e72784910f5830/Configuration/Settings.yaml#L10-L14 are useless, it must be this instead:

Neos:
  Flow:
    psr3:
      Neos\Flow\Log\PsrLoggerFactory:
        systemLogger:
          default:
            class: Flownative\Sentry\Log\SentryFileBackend

[kdambekalns]

After thinking about this as well as getting some feedback, this will be solved, but not by #34. Instead, a logger implementation will be written that can be enabled if wanted, and not be active by default.