* server: split HTTP into its own interface
* move server-http and httplib to its own file
* add the remaining endpoints
* fix exception/error handling
* renaming
* missing header
* fix missing windows header
* fix error responses from http layer
* fix slot save/restore handler
* fix case where only one stream chunk is returned
* add NOMINMAX
* do not call sink.write on empty data
* use safe_json_to_str for SSE
* clean up
* add some comments
* improve usage of next()
* bring back the "server is listening on" message
* more generic handler
* add req.headers
* move the chat template print to init()
* add req.path
* cont : minor
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Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>