Improve some aspects of the recent res partner bank improvement:
- the url toward the docs open in a new tab
- fix the account creation by disabling the readonly when trusted
while the record isn't existing in the database yet
- improve the visual of the setting by putting it in the accounting
section
closes odoo/odoo#120423
Signed-off-by: Quentin De Paoli <qdp@odoo.com>