Stream fuzzing fixes

[whalelephant]

cc: #705

Focused on fuzzing StreamPacket

• when parsing of stream packet data into valid known frames errors, it is returned instead of ignored
• updated a fuzz test name for clarification of cause of failure
• added new test and code for removing trailer bytes for fuzzing

TODO:

• add new test and handle Unknown frames for fuzzing

[koivunej]

Few comments and indentation nits.

[koivunej]

I think this could even be:

type Item = Result<Frame<'a>, WhateverTheErrorIs>;

And instead of returning a FrameIterator from StreamPacket::frames() we could return a impl Iterator<Item = Frame<'a>> which would be constructed from FrameIterator { ... }.map(|res| res.expect("checked at parsing time")).

This would however require some state in the FrameIterator to return None after the first Err return value.

However this isn't something that should be handled right away, perhaps polish at the end if anything.

[koivunej]

Woops, I had forgotten to approve this.