[RFC] use dedicated bridge packages for platform bridges

[stof]

Instead of having a Bridge namespace in the platform package creating lots of optional dependencies (for which we cannot easily tell composer about the supported versions of the dependencies, making it harder to change the range in a BC way), we could have dedicated bridge packages that would have actual requirements for their dependencies (similar to how symfony/mailer and symfony/notifier are dealing with bridges)

[stof]

this also applies to store bridges of course

[chr-hertel]

Yes, definitely 👍