[IMP] web, mail: adapt "Add a Reaction/emoji" icon

Prior to this commit, "Add a Reaction/emoji" and "View Reactions"
buttons had the same icon, which was confusing.

This PR adapts the "Add a Reaction/emoji" icon to make it more
recognizable.

task-3577008

closes odoo/odoo#140481

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

addons/mail/static/src/core/common/message_reaction_button.xml

@@ -2,7 +2,7 @@
 <templates xml:space="preserve">
 
     <t t-name="mail.MessageReactionButton">
-        <button class="btn px-1 py-0 rounded-0" tabindex="1" title="Add a Reaction" aria-label="Add a Reaction" t-ref="emoji-picker"><i class="fa fa-lg fa-smile-o"/></button>
+        <button class="btn px-1 py-0 rounded-0" tabindex="1" title="Add a Reaction" aria-label="Add a Reaction" t-ref="emoji-picker"><i class="oi fa-lg oi-smile-add"/></button>
     </t>
 
 </templates>

addons/mail/static/src/views/web/fields/emojis_field_common/emojis_field_common.xml

@@ -8,7 +8,7 @@
                 t-attf-class="{{positionCenter ? 'pb-0 pt-0' : 'bottom-0'}}"
                 t-ref="emojisButton"
             >
-                <i class="fa fa-smile-o" role="img" aria-label="Emojis"/>
+                <i class="oi oi-smile-add" role="img" aria-label="Emojis"/>
             </button>
         </div>
     </t>

addons/mail/static/tests/web/fields/emojis_fields_tests.js

@@ -18,7 +18,7 @@ export async function testEmojiButtonVisible(selector) {
     await contains(".o_form_editable");
     await contains(selector);
     await contains(`${selector} button`);
-    await contains(`${selector} button .fa-smile-o`);
+    await contains(`${selector} button .oi-smile-add`);
 }
 
 /**

addons/web/static/lib/odoo_ui_icons/style.css

@@ -63,3 +63,4 @@
 .oi-archive:before { content: '\e862'; }
 .oi-unarchive:before { content: '\e863'; }
 .oi-text-effect:before { content: '\e827'; }
+.oi-smile-add:before { content: '\e84e'; }