bug: content persist across edits

[ravener]

Describe the bug

When a command sends a plain text, then another command that sends an embed has been invoked with an edit, the embed gets edited in but the text contents of the previous invocation remain. This might be also related to #166

To Reproduce

1. Invoke command that sends plain text await send(message, 'hello world!');
2. Edit message to invoke some command that sends embed await send(message, { embeds: [embed] });
3. Watch the embed get edited in but the text from step 1 is still visible.

Expected behavior

I expect the previous invocation's data to be completely discarded and the edit acts like a new command invocation so the text should've been emptied in favor of just the embed as the second command requested.

Screenshots

Here I used the eval command q!eval test and edited to the q!stats command and we got this ugly mess.

Additional context

I have not tested it but I suspect the opposite might also happen. i.e embed remaining when the new command is only sending text.