String resource key `parley_accessibility_message_time` should contain variable

[diederv]

AccessibilityUtil.getContentDescriptionEnding() contains the code:

        if (message.getDate() != null) {
            builder.append(context.getString(R.string.parley_accessibility_message_time));
            builder.append(" ");
            builder.append(DateUtil.formatTime(message.getDate()));
        }

in which the date/time is concatenated.
It would be more graceful is the date/time would be injected, for example like this:
"PDF/IMAGE: Bericht van jou. Media bijgevoegd om %1$s"