Fix/manga details buttons (#677)

* Move button icon on top of text on small screens

* Fix colors of buttons

In case a manga is in the library all buttons were colored blue instead of only the library button.
Use white as default color since buttons can also be disabled and with a grey default color it's not easy to tell if the button is disabled or not

* Remove wrapping "button" inside "a" tag

src/components/atoms/CustomIconButton.tsx

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { Button, ButtonProps, Stack, TypographyProps } from '@mui/material';
+
+export const CustomIconButton = <C extends React.ElementType>({
+    children,
+    ...props
+}: ButtonProps & TypographyProps<C, { component?: C }>) => (
+    <Button {...props}>
+        <Stack direction="row" alignItems="center" justifyContent="center" gap="10px" flexWrap="wrap">
+            {children}
+        </Stack>
+    </Button>
+);