scripts/patchreview: Make json output human parsable
Sort dict keys in the json output and use tab spacing. This means
when commited into git, the diffs are human readable but it is more
compact filesize than space indentation.
(From OE-Core rev: bde2ecb203d8a1a29715c70ca3ded382982390cf)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>