Feature: Access tokens for API access (#604)

Co-authored-by: Pranav Raj Sreepuram <pranavrajs@gmail.com>

db/migrate/20200309170810_create_access_tokens.rb

@@ -0,0 +1,23 @@
+class CreateAccessTokens < ActiveRecord::Migration[6.0]
+  def change
+    create_table :access_tokens do |t|
+      t.references :owner, polymorphic: true, index: true
+      t.string :token, index: { unique: true }
+      t.timestamps
+    end
+
+    remove_column :agent_bots, :auth_token, :string
+
+    [::User, ::AgentBot].each do |access_tokenable|
+      generate_access_tokens(access_tokenable)
+    end
+  end
+
+  def generate_access_tokens(access_tokenable)
+    access_tokenable.find_in_batches do |record_batch|
+      record_batch.each do |record|
+        record.create_access_token if record.access_token.blank?
+      end
+    end
+  end
+end

db/migrate/20200309213132_add_account_id_to_agent_bot_inboxes.rb

@@ -0,0 +1,10 @@
+class AddAccountIdToAgentBotInboxes < ActiveRecord::Migration[6.0]
+  def change
+    add_column :agent_bot_inboxes, :account_id, :integer, index: true
+
+    AgentBotInbox.all.each do |agent_bot_inbox|
+      agent_bot_inbox.account_id = agent_bot_inbox.inbox.account_id
+      agent_bot_inbox.save!
+    end
+  end
+end