[FIX] pylint_odoo: The check duplicate-xml-fields skip if the field is inside the search tag

The check duplicate-xml-fields skip the comprobation if the field is inside the search tab

For example

<record model="ir.ui.view" id="view_ir_config_search">
    <field name="model">ir.config_parameter</field>
    <field name="arch" type="xml">
        <search string="System Properties">
            <field name="key_config" context="{'one': 'data'}"/>
            <field name="key_config" context="{'two': 'data'}"/>
        </search>
    </field>
</record>

Fix https://github.com/OCA/pylint-odoo/issues/169

Vauxoo / pylint-odoo

[FIX] pylint_odoo: The check duplicate-xml-fields skip if the field is inside the search tag #136