[IMP] l10n_ae: Added taxes, COA and Fiscal position

- On the invoice pdf, if the invoice is in USD, we
need to specify conversion rate and amounts in AED.
Also, if it is between certain Gulf states, you need
to mention this on the invoice.   'Invoice' also
needs to replaced with 'Tax Invoice'.
- Taxes changed to 0% and 5% / AED symbol on currency
adapted to the real situation of UAE.
- A tax by state automatically adapted with the fiscal
positions in order to have the tax amounts correctly
split by state in the tax report.

opw-1931322

closes odoo/odoo#33385

Signed-off-by: Cedric Snauwaert (csn) <csn@openerp.com>