[IMP] account: easier extension of report

Update invoice report to add id attribute in vat label and tax lines
elements in order to to be able to make clear/save inherit of this
report in Argentinian localization

Before this commit modifying/extending the information was difficult
After this commit, the id can be used for efficient xpath

    <xpath expr="//t[@id='inv_tax_id_label']" position="attributes">
    <xpath expr="//span[@id='line_tax_ids']" position="attributes">

addons/account/views/report_invoice.xml

@@ -6,7 +6,7 @@
                 <t t-set="o" t-value="o.with_context(lang=lang)" />
                 <t t-set="address">
                     <address t-field="o.partner_id" t-options='{"widget": "contact", "fields": ["address", "name"], "no_marker": True}' />
-                    <div t-if="o.partner_id.vat" class="mt16"><t t-esc="o.company_id.country_id.vat_label or 'Tax ID'"/>: <span t-field="o.partner_id.vat"/></div>
+                    <div t-if="o.partner_id.vat" class="mt16"><t t-esc="o.company_id.country_id.vat_label or 'Tax ID'" id="inv_tax_id_label"/>: <span t-field="o.partner_id.vat"/></div>
                 </t>
                 <div class="page">
                     <h2>
@@ -91,7 +91,7 @@
                                             <span t-field="line.discount"/>
                                         </td>
                                         <td t-attf-class="text-left {{ 'd-none d-md-table-cell' if report_type == 'html' else '' }}">
-                                            <span t-esc="', '.join(map(lambda x: (x.description or x.name), line.tax_ids))"/>
+                                            <span t-esc="', '.join(map(lambda x: (x.description or x.name), line.tax_ids))" id="line_tax_ids"/>
                                         </td>
                                         <td class="text-right o_price_total">
                                             <span t-field="line.price_subtotal" groups="account.group_show_line_subtotals_tax_excluded"/>