[MM-16389] Add icon_emoji parameter to webhooks (#11586)

[MM-16389] Add icon_emoji field to posts from incoming webhooks

To be used to substitute the profile picture on posts.

app/import_functions_test.go

@@ -2647,7 +2647,7 @@ func TestImportImportEmoji(t *testing.T) {
 	err := th.App.ImportEmoji(&data, true)
 	assert.NotNil(t, err, "Invalid emoji should have failed dry run")
 
-	emoji, err := th.App.Srv.Store.Emoji().GetByName(*data.Name)
+	emoji, err := th.App.Srv.Store.Emoji().GetByName(*data.Name, true)
 	assert.Nil(t, emoji, "Emoji should not have been imported")
 	assert.NotNil(t, err)
 
@@ -2667,7 +2667,7 @@ func TestImportImportEmoji(t *testing.T) {
 	err = th.App.ImportEmoji(&data, false)
 	assert.Nil(t, err, "Valid emoji should have succeeded apply mode")
 
-	emoji, err = th.App.Srv.Store.Emoji().GetByName(*data.Name)
+	emoji, err = th.App.Srv.Store.Emoji().GetByName(*data.Name, true)
 	assert.NotNil(t, emoji, "Emoji should have been imported")
 	assert.Nil(t, err, "Emoji should have been imported without any error")