Fix UI to administer REST resources

The hierarchy should be:

- Resources (ie. node, user, taxonomy).
- Methods (GET, POST, PATCH, PUT)
- Formats (json, xml...)
- Autentication (cookie, http_basic...)

Ideally each level should toggle automatically.

Each resource AND HTTP method has its own formats and authentication providers.

At the end all this module does is to provide an interface for the settings of rest module. These are written at sites/default/files/config_somelongid/active/rest.settings.yml.

Here is an example of how it looks like. You can see the tree structure that I was trying to resemble in the UI:

resources:
  'entity:node':
    GET: {  }
    POST: {  }
    DELETE: {  }
    PATCH: {  }
  'entity:user':
    GET:
      supported_auth:
        - http_basic
        - oauth
        - cookie
      supported_formats:
        - hal_json
        - json
    POST:
      supported_auth:
        - http_basic
    DELETE:
      supported_auth:
        - http_basic
        - oauth
        - cookie
    PATCH:
      supported_auth:
        - http_basic
        - oauth
        - cookie

Definitively an improvement. Thanks! I have committed it.

I started implementing a simpler approach that resembles the UI to administer Views (see admin/structure/views). Progress can be seen and contributed at branch 2065855-improve-ui.

Now resources are listed as Views UI does it. Pending to add the status of each enabled resource and a select button with operations.

Here is the UI so far at branch 2065855-improve-ui:

Operations are now listed. Pending to implement them. First I want to fix the Description column.

Added description column and implemented dummy handler for Enable/Disable operations.

Fixed.

Here are two attachments of how the new UI looks like.

List of all resources (enabled and then disabled). The Enabled ones have a description column:

And this is the edit page for an enabled resource (thanks @capynet for the tips on theming):