api: factorize SWHRemoteAPI.(get|post)_stream methods
- merge raw_post and row_get in a unique raw_verb method,
- merge post_stream() and post() as a unique post(); post_strean is then a call to post with the 'stream' parameter set,
- merge get_stream() and get() the same.
Migrated from D1259 (view on Phabricator)