[IMP] account: add cumulated balance for general ledger list view

Task 2081612
* Add as an optionnal field "balance" (simple debit -credit)
  - usefull for "group by"
  - usefull when selecting several lines (in the footer total)
  - Hidden by default for journal view
  - Diplayed by default for ledger view
* Cumulative balance only for ledger views

closes odoo/odoo#38174

Related: odoo/enterprise#8024
Signed-off-by: Quentin De Paoli (qdp) <qdp@openerp.com>