Create the settings and schema files

Problem/Motivation

In Drupal 7 we can use the variable_set() and variable_get() function to work with the module configuration variables, but in Drupal 8 we need to use the Simple Configuration API

Proposed resolution

Create the node_revision_delete.settings.yml and node_revision_delete.schema.yml files to be used for the module configuration.

Remaining tasks

None.

User interface changes

None.

API changes

None.

Data model changes

None.