IPLD Prime leftover bugs

[aschmahmann]

Description

• Missing test for hang when doing dag get: 9339e82 #8377
• Bugs related to codecs that return EOF on encode/decode (EOF error are ignored by CLI so we would need to either fix that or wrap the errors) #8378
• Not clear what "raw" means in various CLI flags relating to format, or how to get those behaviors #8376

#7976 (comment)

[warpfork]

I'm breaking all three of these out into their own issues. They are all sizable, and none of them has anything to do with each other, and they are not likely to be equal importance nor urgency either.

Some of them aren't even actually from #7976 at all, they were just discovered for the first time during the unusually deep effort made to validate that work.