Refactor to use wacz2car for ipfs car serialization.

[ikreymer]

wacz2car will be refactored to use the same serialization strategy (webrecorder/wacz2car#2)
After webrecorder/wacz2car#3 and webrecorder/wacz2car#5 are implemented, this library should be refactored to use wacz2car, which will support the same serialization