Better handle lack of space

When device is full:

• Recording stops (ok)
• Encoding can start (ok)
• Encoding failed (expected)
• Storing raw wav is suggested (ok)
• If any of this fails/is canceled the raw temporary file is preserved (ok)

What could be improved is that afterwards, if saving/encoding failed, the temporary file lays inside /data/ in a "hidden" way (not shown from the UI).

Since we lack space, I suggest to allow "sharing" the temporary file (raw or encoded, so that it can be uploaded or to encoding and upload on the fly)