[ADD] l10n_ec: Improve accounts in chart template

- Adds early pay discounts, cash dicounts accounts
- Sets the ecuadorian chart of accounts as updatable (same as most
localizations)
- Fix the account type, many should be liability current and not liability payable (otherwise the usage of these accounts affects the payable/receivable reports)

closes odoo/odoo#118559

Signed-off-by: Josse Colpaert <jco@odoo.com>