This reverts commit dc1d6ce4bf7390e23b73d96634ff87ca9341e129.
We need to revert this commit because
the waku-simulator stopped working. i.e. the nodes couldn't establish
connections among them: 054ba9e33f
Also, the following js-waku test fails due to this commit:
"same cluster, different shard: nodes connect"
* waku_lightpush/protocol.nim: minor changes to make it compile after revert
* Allow text/plain content type descriptor for json formatted content body. Refactored duplicated encode/decode functions for rest api
* Fix relay endpoint decodings of content bodies to accept text/plain
* Added support for content body decoder for checking media type if additional parameters are present
* Fix wrong usage of ContentTypeData - appeared only for tests
