Add Fragmentation support for WebRTC

[thelsing]

Identify the Bug or Feature request

• fixes java.lang.IllegalArgumentException: when multiple backup campaigns have same time stamp #3112
• related to "Productionizing" WebRTC functionality #2945

Description of the Change

• the campaign object and assets are to large to send them in one package. As WebRTC only supports around 16 KB package size, we have to fragment bigger messages. This PR implements this.
• I also added some debug logging for sending and receiving messages between client and server.
• As an additional bonus I included a one line fix for java.lang.IllegalArgumentException: when multiple backup campaigns have same time stamp #3112

Possible Drawbacks

None.

Documentation Notes

None.

Release Notes

• Add Fragmentation support for WebRTC
• Fix java.lang.IllegalArgumentException: when multiple backup campaigns have same time stamp #3112

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This change is 

[cwisniew]

Reviewed 7 of 7 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @thelsing)