Several users have asked to be able to send asynchronous voice messages (voice notes). This request was previously recorded under #985 (voice/video calls) but I'm moving it to its own ticket as the requirements and implementation are different. Relevant comments from #985: * https://code.briarproject.org/briar/briar/-/issues/985#note_28705 * https://code.briarproject.org/briar/briar/-/issues/985#note_44100 * https://code.briarproject.org/briar/briar/-/issues/985#note_47061