[Feature Request] MultiTrack Audio Support

Currently, Kdenlive does not support multitrack audio at all. [ME] Each channel must be on a seperate track so they can be edited individually.
Here is a screenshot of another video editor that does support Multitrack Audio:

And here is Kdenlive not having that Feature:

I actually started using MultiTrack Audio recordings to have more time spent on editing and making the video more professional. Kdenlive needs to have this.

Edit [ME]
https://bugs.kde.org/show_bug.cgi?id=394164

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see Cafe#42, Audio Workflow.

• #754: enable "separate channels". Merge all streams -> put the clip into the timeline -> the audio part of the clip show no channels, is just green.
• #754: Merge selected not yet implemented.
• #754: shortcut key for the sources menu and the option to add more tracks in one operation we have a convenient and complete stereo environment.
• #754: MLT Audiomap is able to manage up tl 32 channels (same as all the professional applications). https://www.mltframework.org/plugins/FilterAudiomap/
• #754: MLT Channelmap: managing a cetain number of channels and to map them in output order: https://www.mltframework.org/plugins/FilterAvfilter-channelmap/
• Even if I have enough audio tracks open it shows "Not enough audio tracks for all streams".
• A pop up would be helpful like "would you like to create the missing Audio tracks?"
• Enable merge all streams in clip monitor is not possible
• Enable merge all streams -> still all selected streams get on the timeline
• Clip with 1 stream: no wave form visible in clip monitor
• all streams as default, with a setting option to only import the x first streams.
• Hold "meta" for moving 1 of 3 audio streams to another track -> moves all 3 streams together
• Choose stream 1&3. Drag the clip from clip monitor to the timeline -> only stream 1 gets added.
• Drag the clip from project bin to the timeline -> I get a freeze. Looks like the comma/dot issue.
• Deselecting all streams -> with the last deselection Kdenlive crash.
• We should be able to add the number of tracks we want to add in the Insert track dialogue
• Add quick effects to audio streams (swap/copy channels, normalize, gain)