Move TrainingProviders to Providers module

[inulty-dfe]

Context

TrainingProviders controller currently sits outside the Providers module despite it looking for all intents and purposes as depending on the provider.

In order to make sensible changes further down the line WRT to how Accredited providers view Training providers and vice versa, I propose we move the TrainingProviders module into the Providers module for consistency.

Changes proposed in this pull request

Move modules in a refactoring without changing any behaviour

module Publish
  module TrainingProvidersController


### To

module Publish
  module Providers
    module TrainingProvidersController

The use of this controller is for the AccreditedProvider to be able to see the courses of their training providers

training-providers	training-providers/A01/courses

Guidance to review

[inulty-dfe]

Tech debt: Move TrainingProviders to the Provider module