Allow configuring the exported tables from application.conf

[AlexITC]

Right now, we need to write a guice module to expose the TableSettings (example), which defines the tables that are exposed to admin users.

Let's create a module like DataExplorerConfigModule which loads DataExplorerSettings from `application.conf.

As an example, we should be able to write this piece in application.conf which will be imported by the new module:

dataExplorerSettings = {
  tables = [
    {
      tableName = "users",
      primaryKeyField = "user_id"
    }
  ]
}