Update docs and change/tidy some related APIs

[benjie]

• 🚨 hookArgs has swapped the order of the second and third arguments, so that it matches grafast. It's now hookArgs(args, resolvedPreset, ctx). Please search your code for hookArgs and update it.
• 🚨 preset.server.eventStreamRoute is now preset.server.eventStreamPath to match the graphqlPath and graphiqlPath options. This does not affect makeV4Preset({ eventStreamRoute: ... }).
• 🚨 PgRBACPlugin is now included by default, you can disable it via disablePlugins: ['PgRBACPlugin']. Users of makeV4Preset() are unaffected.
• 🚨 pgConfig.pubsub now defaults to true (we support LISTEN/NOTIFY by default unless you turn it off)
• 🚨 listenWithPgClientFromPgConfig is no more; please use pgConfig.pgSubscriber instead
• 🚨 pgl.getServerParams() is now pgl.getSchemaResult()
• ✨ Watch mode now works in Ruru, and without the hacks V4 used! My GraphiQL PR that means that schema replacement should not break the navigation stack was merged; I've updated Ruru to include this fix
• ✨ makeV4Preset() now supports eventStreamRoute option
• 💅 grafastSync() now supports the same options as grafast()
• 💅 pgConfig.listen removed, it was redundant versus pgConfig.pgSubscriber
• 💅 Removed preset.schema.subscriptions option which didn't do anything
• 💅 graphile config print now omits undefined values
• 📖 Significant documentation updates