[FIX] mail: set automatic email signature from correct company

When sending an email from a multi-company environment, the automatic
email signature is not corresponding to the company from which the email
is sent.

This is because the user context is not properly forwarded, in
particular the `allowed_company_ids` key.

The issue comes from the new rpc service not autmatically adding the
user context to the request, whereas the legacy rpc service did.

opw-3394780

closes odoo/odoo#132684

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/models/composer_view/composer_view.js

@@ -7,6 +7,8 @@ import { clear, insertAndReplace, link, replace, unlink, unlinkAll } from '@mail
 import { OnChange } from '@mail/model/model_onchange';
 import { addLink, escapeAndCompactTextContent, parseAndTransform } from '@mail/js/utils';
 
+import session from "web.session";
+
 function factory(dependencies) {
 
     class ComposerView extends dependencies['mail.model'] {
@@ -298,6 +300,7 @@ function factory(dependencies) {
                 if (this.threadView && this.threadView.replyingToMessageView && this.threadView.thread !== this.messaging.inbox) {
                     postData.parent_id = this.threadView.replyingToMessageView.message.id;
                 }
+                params.context = Object.assign(params.context || {}, session.user_context);
                 const chatter = this.chatter;
                 const { threadView = {} } = this;
                 const { thread: chatterThread } = this.chatter || {};