Remove customemojimodel_p.h

It's been unused for a long time

src/models/customemojimodel_p.h

@@ -1,20 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Carson Black <uhhadd@gmail.com>
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#pragma once
-
-#include "customemojimodel.h"
-#include <QRegularExpression>
-
-class NeoChatConnection;
-
-struct CustomEmoji {
-    QString name; // with :semicolons:
-    QString url; // mxc://
-    QRegularExpression regexp;
-};
-
-struct CustomEmojiModel::Private {
-    QPointer<NeoChatConnection> connection;
-    QList<CustomEmoji> emojies;
-};