[FIX+IMP] rma, rma_sale: fix bugs and add improvements

- Fix thrown error when trying to download a picking from the portal.
- Add the hook method to prepare RMA values ​​from the return pick wizard.
- Add the access rule for portal users.
- Show the portal 'Request RMAs' button on the sales page only to users
related to the sales order.

[UPD] Update rma.pot

rma 12.0.1.3.0

Update translation files

Updated by "Update PO files to match POT (msgmerge)" hook in Weblate.

Translation: rma-12.0/rma-12.0-rma
Translate-URL: https://translation.odoo-community.org/projects/rma-12-0/rma-12-0-rma/

rma/data/mail_data.xml

@@ -5,7 +5,7 @@
         <field name="name">Draft RMA</field>
         <field name="res_model">rma</field>
         <field name="default" eval="False"/>
-        <field name="description">New RMA in draft state</field>
+        <field name="description">RMA in draft state</field>
     </record>
     <!-- rma_team-related subtypes for messaging / Chatter -->
     <record id="mt_rma_team_rma_draft" model="mail.message.subtype">