Rudder plugins

Right now, plugins can't use the "with-cached-resources" directive that allows to versionned & cache plugin resources.

This is needed to avoid the case where the plugin changed css/js and the user updated it.

We also need to be more specific for plugin resources than just rudder version because the plugin can change its resources with its version.

So we propose to:

- update with-cached-resource to special case plugin resource rewrite
- we know we are dealing with a plugin resources because the url looks like "toserver/plugin-short-id".
- in that case, we also add plugin version with a pending "?plugin-version". That will allows to invalidate browser cache WITHOUT needing to modify the caching scheme on rudder side.

It may need a breaking in plugin management code so that we have a easy way to find back plugin information based on their id (so -> Rudder 4.3 only)