[IMP] Useability and misc fixes in POS

addons/account/account_bank_statement.py

addons/account/account_cash_statement.py

addons/account/account_view.xml

addons/point_of_sale/account_bank_statement.py

addons/point_of_sale/account_statement_demo.xml

addons/point_of_sale/account_statement_view.xml

addons/point_of_sale/point_of_sale_demo.xml

addons/point_of_sale/point_of_sale_view.xml

addons/point_of_sale/test/00_register_open.yml

addons/point_of_sale/wizard/pos_box_entries.py

addons/point_of_sale/wizard/pos_close_statement.py

addons/point_of_sale/wizard/pos_open_statement.py

addons/sale/report/sale_report_view.xml