refs #9601
Example:
```
collections:
/podcast/:
permalink: /{slug}/
```
- the name of the collection is remembered as `routerName` (in the case above: "podcast")
- the name of the collection is important for two things
1. context value
2. template name
- the context value is available for specific theme helpers e.g. is helper, body_class helper
- we auto-lookup the collection name in your theme e.g. podcast.hbs
- this logic does not apply to static routes
- if you define templates on your collection, they are stronger than the collection name
closes https://github.com/TryGhost/Ghost/issues/9674
- with dynamic routing the first collection get's the "index" context attached
- the index context signalises the main post listening route (first collection)
- this behaviour was present < 1.24 - we have to keep this behaviour
refs #9601
### Dynamic Routing
This is the beta version of dynamic routing.
- we had a initial implementation of "channels" available in the codebase
- we have removed and moved this implementation
- there is now a centralised place for dynamic routing - server/services/routing
- each routing component is represented by a router type e.g. collections, routes, static pages, taxonomies, rss, preview of posts
- keep as much as possible logic of routing helpers, middlewares and controllers
- ensure test coverage
- connect all the things together
- yaml file + validation
- routing + routers
- url service
- sitemaps
- url access
- deeper implementation of yaml validations
- e.g. hard require slashes
- ensure routing hierarchy/order
- e.g. you enable the subscriber app
- you have a custom static page, which lives under the same slug /subscribe
- static pages are stronger than apps
- e.g. the first collection owns the post it has filtered
- a post cannot live in two collections
- ensure apps are still working and hook into the routers layer (or better said: and register in the routing service)
- put as much as possible comments to the code base for better understanding
- ensure a clean debug log
- ensure we can unmount routes
- e.g. you have a collection permalink of /:slug/ represented by {globals.permalink}
- and you change the permalink in the admin to dated permalink
- the express route get's refreshed from /:slug/ to /:year/:month/:day/:slug/
- unmount without server restart, yey
- ensure we are backwards compatible
- e.g. render home.hbs for collection index if collection route is /
- ensure you can access your configured permalink from the settings table with {globals.permalink}
### Render 503 if url service did not finish
- return 503 if the url service has not finished generating the resource urls
### Rewrite sitemaps
- we have rewritten the sitemaps "service", because the url generator does no longer happen on runtime
- we generate all urls on bootstrap
- the sitemaps service will consume created resource and router urls
- these urls will be shown on the xml pages
- we listen on url events
- we listen on router events
- we no longer have to fetch the resources, which is nice
- the urlservice pre-fetches resources and emits their urls
- the urlservice is the only component who knows which urls are valid
- i made some ES6 adaptions
- we keep the caching logic -> only regenerate xml if there is a change
- updated tests
- checked test coverage (100%)
### Re-work usage of Url utility
- replace all usages of `urlService.utils.urlFor` by `urlService.getByResourceId`
- only for resources e.g. post, author, tag
- this is important, because with dynamic routing we no longer create static urls based on the settings permalink on runtime
- adapt url utility
- adapt tests
