CSV Imports Overhaul (Transactions, Trades, Accounts, and Mint import support) (#1209)

* Remove stale 1.0 import logic and model

* Fresh start

* Checkpoint before removing nav

* First working prototype

* Add trade, account, and mint import flows

* Basic working version with tests

* System tests for each import type

* Clean up mappings flow

* Clean up PR, refactor stale code, tests

* Add back row validations

* Row validations

* Fix import job test

* Fix import navigation

* Fix mint import configuration form

* Currency preset for new accounts

app/models/account_import.rb

@@ -0,0 +1,49 @@
+class AccountImport < Import
+  def import!
+    transaction do
+      rows.each do |row|
+        mapping = mappings.account_types.find_by(key: row.entity_type)
+        accountable_class = mapping.value.constantize
+
+        account = family.accounts.build(
+          name: row.name,
+          balance: row.amount.to_d,
+          currency: row.currency,
+          accountable: accountable_class.new,
+          import: self
+        )
+
+        account.save!
+      end
+    end
+  end
+
+  def mapping_steps
+    [ Import::AccountTypeMapping ]
+  end
+
+  def required_column_keys
+    %i[name amount]
+  end
+
+  def column_keys
+    %i[entity_type name amount currency]
+  end
+
+  def dry_run
+    {
+      accounts: rows.count
+    }
+  end
+
+  def csv_template
+    template = <<-CSV
+      Account type*,Name*,Balance*,Currency
+      Checking,Main Checking Account,1000.00,USD
+      Savings,Emergency Fund,5000.00,USD
+      Credit Card,Rewards Card,-500.00,USD
+    CSV
+
+    CSV.parse(template, headers: true)
+  end
+end