Add account migration UI (#11846)

Fix #10736

- Change data export to be available for non-functional accounts
- Change non-functional accounts to include redirecting accounts

db/migrate/20190914202517_create_account_migrations.rb

@@ -0,0 +1,12 @@
+class CreateAccountMigrations < ActiveRecord::Migration[5.2]
+  def change
+    create_table :account_migrations do |t|
+      t.belongs_to :account, foreign_key: { on_delete: :cascade }
+      t.string :acct, null: false, default: ''
+      t.bigint :followers_count, null: false, default: 0
+      t.belongs_to :target_account, foreign_key: { to_table: :accounts, on_delete: :nullify }
+
+      t.timestamps
+    end
+  end
+end

db/migrate/20190915194355_create_account_aliases.rb

@@ -0,0 +1,11 @@
+class CreateAccountAliases < ActiveRecord::Migration[5.2]
+  def change
+    create_table :account_aliases do |t|
+      t.belongs_to :account, foreign_key: { on_delete: :cascade }
+      t.string :acct, null: false, default: ''
+      t.string :uri, null: false, default: ''
+
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -15,6 +15,15 @@ ActiveRecord::Schema.define(version: 2019_09_17_213523) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
+  create_table "account_aliases", force: :cascade do |t|
+    t.bigint "account_id"
+    t.string "acct", default: "", null: false
+    t.string "uri", default: "", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["account_id"], name: "index_account_aliases_on_account_id"
+  end
+
   create_table "account_conversations", force: :cascade do |t|
     t.bigint "account_id"
     t.bigint "conversation_id"
@@ -49,6 +58,17 @@ ActiveRecord::Schema.define(version: 2019_09_17_213523) do
     t.index ["account_id"], name: "index_account_identity_proofs_on_account_id"
   end
 
+  create_table "account_migrations", force: :cascade do |t|
+    t.bigint "account_id"
+    t.string "acct", default: "", null: false
+    t.bigint "followers_count", default: 0, null: false
+    t.bigint "target_account_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["account_id"], name: "index_account_migrations_on_account_id"
+    t.index ["target_account_id"], name: "index_account_migrations_on_target_account_id"
+  end
+
   create_table "account_moderation_notes", force: :cascade do |t|
     t.text "content", null: false
     t.bigint "account_id", null: false
@@ -768,10 +788,13 @@ ActiveRecord::Schema.define(version: 2019_09_17_213523) do
     t.index ["user_id"], name: "index_web_settings_on_user_id", unique: true
   end
 
+  add_foreign_key "account_aliases", "accounts", on_delete: :cascade
   add_foreign_key "account_conversations", "accounts", on_delete: :cascade
   add_foreign_key "account_conversations", "conversations", on_delete: :cascade
   add_foreign_key "account_domain_blocks", "accounts", name: "fk_206c6029bd", on_delete: :cascade
   add_foreign_key "account_identity_proofs", "accounts", on_delete: :cascade
+  add_foreign_key "account_migrations", "accounts", column: "target_account_id", on_delete: :nullify
+  add_foreign_key "account_migrations", "accounts", on_delete: :cascade
   add_foreign_key "account_moderation_notes", "accounts"
   add_foreign_key "account_moderation_notes", "accounts", column: "target_account_id"
   add_foreign_key "account_pins", "accounts", column: "target_account_id", on_delete: :cascade