feat: add Google login flow and inbox creation (#9580)

This PR adds the following changes

1. Refactor `microsoft/callbacks_controller` to move common logic to
`oauth_callback_controller`, most of the logic is re-used for Google
2. Add UI components, `googleClient` and I18n entries for Google login
3. Add Google callback and inbox creation
4. Add a `joinUrl` utility along with specs (need to move it to utils)
5. Add `GoogleConcern`, `Google::AuthorizationsController` and
`Google::CallbacksController`

> Note: The UI is hidden for now, so we can merge this without any
hiccups, to enable it just revert the commit `05c18de`

### Preview


https://github.com/chatwoot/chatwoot/assets/18097732/1606d150-4561-49dc-838d-e0b00fe49ce3

### Linear Tickers

[CW-3370](https://linear.app/chatwoot/issue/CW-3370)
[CW-3371](https://linear.app/chatwoot/issue/CW-3371)

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/controllers/oauth_callback_controller.rb

@@ -0,0 +1,108 @@
+class OauthCallbackController < ApplicationController
+  def show
+    @response = oauth_client.auth_code.get_token(
+      oauth_code,
+      redirect_uri: "#{base_url}/#{provider_name}/callback"
+    )
+
+    handle_response
+    ::Redis::Alfred.delete(cache_key)
+  rescue StandardError => e
+    ChatwootExceptionTracker.new(e).capture_exception
+    redirect_to '/'
+  end
+
+  private
+
+  def handle_response
+    inbox, already_exists = find_or_create_inbox
+
+    if already_exists
+      redirect_to app_email_inbox_settings_url(account_id: account.id, inbox_id: inbox.id)
+    else
+      redirect_to app_email_inbox_agents_url(account_id: account.id, inbox_id: inbox.id)
+    end
+  end
+
+  def find_or_create_inbox
+    channel_email = Channel::Email.find_by(email: users_data['email'], account: account)
+    # we need this value to know where to redirect on sucessful processing of the callback
+    channel_exists = channel_email.present?
+
+    channel_email ||= create_channel_with_inbox
+    update_channel(channel_email)
+
+    # reauthorize channel, this code path only triggers when microsoft auth is successful
+    # reauthorized will also update cache keys for the associated inbox
+    channel_email.reauthorized!
+
+    [channel_email.inbox, channel_exists]
+  end
+
+  def update_channel(channel_email)
+    channel_email.update!({
+                            imap_login: users_data['email'], imap_address: imap_address,
+                            imap_port: '993', imap_enabled: true,
+                            provider: provider_name,
+                            provider_config: {
+                              access_token: parsed_body['access_token'],
+                              refresh_token: parsed_body['refresh_token'],
+                              expires_on: (Time.current.utc + 1.hour).to_s
+                            }
+                          })
+  end
+
+  def provider_name
+    raise NotImplementedError
+  end
+
+  def oauth_client
+    raise NotImplementedError
+  end
+
+  def cache_key
+    "#{provider_name}::#{users_data['email'].downcase}"
+  end
+
+  def create_channel_with_inbox
+    ActiveRecord::Base.transaction do
+      channel_email = Channel::Email.create!(email: users_data['email'], account: account)
+      account.inboxes.create!(
+        account: account,
+        channel: channel_email,
+        name: users_data['name'] || fallback_name
+      )
+      channel_email
+    end
+  end
+
+  def users_data
+    decoded_token = JWT.decode parsed_body[:id_token], nil, false
+    decoded_token[0]
+  end
+
+  def account_id
+    ::Redis::Alfred.get(cache_key)
+  end
+
+  def account
+    @account ||= Account.find(account_id)
+  end
+
+  # Fallback name, for when name field is missing from users_data
+  def fallback_name
+    users_data['email'].split('@').first.parameterize.titleize
+  end
+
+  def oauth_code
+    params[:code]
+  end
+
+  def base_url
+    ENV.fetch('FRONTEND_URL', 'http://localhost:3000')
+  end
+
+  def parsed_body
+    @parsed_body ||= @response.response.parsed
+  end
+end