Improve presenter architecture

app/presenters/build_presenter.rb

app/presenters/ci/build/presenter.rb

app/presenters/ci/variable/presenter.rb

app/presenters/variable_presenter.rb

lib/gitlab/view/presenter/base.rb

lib/gitlab/view/presenter/delegated.rb

lib/gitlab/view/presenter/simple.rb

spec/lib/gitlab/view/presenter/base_spec.rb

spec/lib/gitlab/view/presenter/delegated_spec.rb

spec/lib/gitlab/view/presenter/simple_spec.rb

spec/lib/gitlab/view/presenter_spec.rb

spec/presenters/build_presenter_spec.rb

spec/presenters/ci/build/presenter_spec.rb

spec/presenters/ci/variable/presenter_spec.rb