fix dag test fixtures for go-ipld-prime codecs

[rvagg]

Pending ipld/go-ipld-prime#202 and ipld/go-ipld-prime#203

• I've massaged one of the main fixtures so that it's pre-sorted according to DAG-CBOR rules since go-ipld-prime as yet doesn't apply any sorting, I didn't want to treat that as a blocker for this PR but it may have to be treated as a blocker for release (similar change to Sort map entries marshalling dag-json ipld/go-ipld-prime#203, but there's deep background here ... cans of worms).
• dag get doesn't print a newline now, which I think is the right behaviour since it can now do any codec and newlines are going to be a problem for the stricter binary formats than dag-json, so I've adapted the fixtures.
• The proper DAG-PB Data / Links changes show up here and are now correct, as are the new (proper) rules for showing bytes with DAG-JSON.
• There's a change near the bottom for dag stat, this comes from go-ipld-cbor doing always-64-bit integers, but we're now doing always-smallest-possible now across all our codecs, so go-ipld-cbor is the odd one out (old and new JS codecs do this, and spec says it).

[willscott]

thanks for digging through these!

[rvagg]

Now using go-ipld-prime master with DAG-JSON sorting and no whitespace. Still having trouble with the full sharness run in Circle but will merge this into the feat/dag-put-ipld-prime when CI is done if it doesn't throw up anything new. The sharness problems can be worked on in that branch.