Composer: Use conflict and suggest properties

[core23]

As mentioned in https://github.com/sonata-project/SonataClassificationBundle/pull/183, we should use the suggest property in the way it has been designed.

Some bundles use them as a normal required property, instead of leaving a message for this. The version information should be moved to the conflicts property.

Some bundles that I found so far:

• [x] SonataBlockBundle
• [x] SonataClassificationBundle
• [x] SonataDashboardBundle
• [x] SonataExporter
• [ ] SonataMediaBundle
• [x] SonataNewsBundle
• [ ] SonataNotificationBundle
• [x] SonataPageBundle
• [x] SonataSeoBundle
• [ ] SonataUserBundle

[VincentLanglet]

I opened a PR for the three repository