Change name of config object

Problem/Motivation

Two different configuration object names are being used in this module:

- socialfeed.facebook.settings (in config/install and confi/schema)
- socialfeed.facebooksettings (elsewhere)

The same goes for socialfeed.twitter.settings and socialfeed.instagram.settings

Steps to reproduce

You notice this when you install and configure the module and export the config. This will result in duplicate config yml files.

Proposed resolution

Rename config according to names in config/install.

So e.g socialfeed.facebooksettings becomes socialfeed.facebook.settings

Remaining tasks

Test the patch

User interface changes

None

API changes

None

Data model changes

No more duplicate config