[FIX] mail: good showing of avatar in discuss invitation screen

Follow-up of MILK web client redesign.

Before this commit, the avatar and im status in invitation popover
in discuss app were not showing properly: avatar not rounded,
and im status mispositionned in top-right corner.

This commit fixes the issue by absolutely positioning im status
like all other uses of IM status on top of user avatar.

closes odoo/odoo#122459

X-original-commit: 6061d4e718a8e15a1448c236414e8326ba5e13c5
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/mail/static/src/discuss/channel_invitation.xml

@@ -15,7 +15,7 @@
                                 <div class="o-discuss-ChannelInvitation-avatar position-relative d-flex flex-shrink-0 bg-100">
                                     <img class="w-100 h-100 rounded-circle o_object_fit_cover o_redirect"
                                          t-att-src="threadService.avatarUrl(selectablePartner, props.thread)"/>
-                                    <ImStatus persona="selectablePartner"/>
+                                    <ImStatus persona="selectablePartner" className="'position-absolute top-100 start-100 translate-middle mt-n1 ms-n1'"/>
                                 </div>
                             </div>
                             <span class="flex-grow-1 mx-2 text-truncate fs-6" t-esc="selectablePartner.name"/>