Refactor contact mailer

- Send single email with new email in `to` and old email in `bcc` fields
- Remove `Que::Mailer` (#895)
- Add preview
- DRY templates
- Add tests
- Extract translations
- Remove useless specs

spec/views/mailers/contact_mailer/email_updated.html.erb_spec.rb

@@ -1,32 +0,0 @@
-require 'rails_helper'
-
-RSpec.describe 'mailers/contact_mailer/email_updated.html.erb' do
-  let(:contact) { instance_spy(Contact) }
-  let(:contact_presenter) { instance_spy(RegistrantPresenter) }
-  let(:registrar_presenter) { instance_spy(RegistrarPresenter) }
-
-  before :example do
-    allow(RegistrantPresenter).to receive(:new).and_return(contact_presenter)
-    allow(RegistrarPresenter).to receive(:new).and_return(registrar_presenter)
-
-    assign(:contact, contact)
-    assign(:old_email, 'test@test.com')
-
-    stub_template 'mailers/shared/registrant/_registrant.et.html' => ''
-    stub_template 'mailers/shared/registrant/_registrant.en.html' => ''
-    stub_template 'mailers/shared/registrar/_registrar.et.html' => ''
-    stub_template 'mailers/shared/registrar/_registrar.en.html' => ''
-  end
-
-  it 'has affected domain list in estonian' do
-    expect(contact_presenter).to receive(:domain_names_with_roles).with(locale: :et, line_break: '<br>').and_return('test domain list et')
-    render
-    expect(rendered).to have_text('test domain list et')
-  end
-
-  it 'has affected domain list in english' do
-    expect(contact_presenter).to receive(:domain_names_with_roles).with(line_break: '<br>').and_return('test domain list en')
-    render
-    expect(rendered).to have_text('test domain list en')
-  end
-end

spec/views/mailers/contact_mailer/email_updated.text.erb_spec.rb

@@ -1,32 +0,0 @@
-require 'rails_helper'
-
-RSpec.describe 'mailers/contact_mailer/email_updated.text.erb' do
-  let(:contact) { instance_spy(Contact) }
-  let(:contact_presenter) { instance_spy(RegistrantPresenter) }
-  let(:registrar_presenter) { instance_spy(RegistrarPresenter) }
-
-  before :example do
-    allow(RegistrantPresenter).to receive(:new).and_return(contact_presenter)
-    allow(RegistrarPresenter).to receive(:new).and_return(registrar_presenter)
-
-    assign(:contact, contact)
-    assign(:old_email, 'test@test.com')
-
-    stub_template 'mailers/shared/registrant/_registrant.et.text' => ''
-    stub_template 'mailers/shared/registrant/_registrant.en.text' => ''
-    stub_template 'mailers/shared/registrar/_registrar.et.text' => ''
-    stub_template 'mailers/shared/registrar/_registrar.en.text' => ''
-  end
-
-  it 'has affected domain list in estonian' do
-    expect(contact_presenter).to receive(:domain_names_with_roles).with(locale: :et).and_return('test domain list et')
-    render
-    expect(rendered).to have_text('test domain list et')
-  end
-
-  it 'has affected domain list in english' do
-    expect(contact_presenter).to receive(:domain_names_with_roles).and_return('test domain list en')
-    render
-    expect(rendered).to have_text('test domain list en')
-  end
-end