* swarm/api: url scheme bzz-hash to get hashes of swarm content (#15238)
Update URI to support bzz-hash scheme and handle such HTTP requests by
responding with hash of the content as a text/plain response.
* swarm/api: return hash of the content for bzz-hash:// requests
* swarm/api: revert "return hash of the content for bzz-hash:// requests"
Return hashes of the content that would be returned by bzz-raw
request.
* swarm/api/http: handle error in TestBzzGetPath
* swarm/api: remove extra blank line in comment