closes#9528
These code changes introduce a YAML parser which will load and parse YAML files from the `/content/settings` directory. There are three major parts involved:
1. `ensure-settings.js`: this fn takes care that on bootstrap, the supported files are present in the `/content/settings` directory. If the files are not present, they get copied back from our default files. The default files to copy from are located in `core/server/services/settings`.
2. `loader.js`: the settings loader reads the requested `yaml` file from the disk and passes it to the yaml parser, which returns a `json` object of the file. The settings loader throws an error, if the file is not accessible, e. g. because of permission errors.
3. `yaml-parser`: gets passed a `yaml` file and returns a `json` object. If the file is not parseable, it returns a clear error that contains the information, what and where the parsing error occurred (e. g. line number and reason).
- added a `get()` fn to settings services, that returns the settings object that's asked for. e. g. `settings.get('routes').then(()...` will return the `routes` settings.
- added a `getAll()` fn to settings services, that returns all available settings in an object. The object looks like: `{routes: {routes: {}, collections: {}, resources: {}}, globals: {value: {}}`, assuming that we have to supported settings `routes` and `globals`.
Further additions:
- config `contentPath` for `settings`
- config overrides for default `yaml` files location in `/core/server/services/settings`
**Important**: These code changes are in preparation for Dynamic Routing and not yet used. The process of copying the supported `yaml` files (in this first step, the `routes.yaml` file) is not yet activated.
