Remote Audio Transcription and Idle Client

[gfd2020]

Remote audio transcription with the IPED server/client is excellent. It helps a lot in this difficult task.
However, I noticed something that could perhaps improve performance a little.
For example: a UFDR report has photos, spreadsheets, chats, audio, etc. When the client identifies audio it will send it to the remote server. But sometimes it uses all threads to send to the server, so it remains idle and waiting for the result. Perhaps we could configure a maximum number of transcription threads if it have other types of files not yet processed (maybe half), so as not to leave the client inactive and doing other tasks.

This issue is being addressed in PR #2023