Add loan start date

[tonyvince]

close #1605

[zachgoll]

@tonyvince I think to solve this one, we'll need to take a slightly different approach. Adding a start_date to an Account conflicts with our existing model that relies solely on Account::Valuation and Account::Transaction entries to calculate the historical balance of an account.

A possible approach here would be to include a origination_date and origination_loan_balance field in the initial form the user fills out and then use that information to create an Account::Valuation representing the "starting loan amount".

Currently, for all accounts we're calling create_and_sync which generates 2 valuations by default:

maybe/app/models/account.rb

Lines 58 to 85 in 413ec6c

	def create_and_sync(attributes)
	attributes[:accountable_attributes] ||= {} # Ensure accountable is created, even if empty
	account = new(attributes.merge(cash_balance: attributes[:balance]))
	transaction do
	# Create 2 valuations for new accounts to establish a value history for users to see
	account.entries.build(
	name: "Current Balance",
	date: Date.current,
	amount: account.balance,
	currency: account.currency,
	entryable: Account::Valuation.new
	)
	account.entries.build(
	name: "Initial Balance",
	date: 1.day.ago.to_date,
	amount: 0,
	currency: account.currency,
	entryable: Account::Valuation.new
	)
	account.save!
	end
	account.sync_later
	account
	end
	end

For loan accounts, we likely want to "specialize" this behavior so that instead of blindly creating a valuation of 0 a day ago, we create a valuation on the origination_date with an amount equal to origination_loan_balance.