Some fixes for non-ASCII chars in MPD uris

[kingosticks]

Fixes #1759

Most of this comes from Track uris being bytes but falling over when formatted with unicode strings for output / logging. And then I went a bit mad sprinkling non-ASCII throughout the tests.

[codecov]

Codecov Report

Merging #1805 into release-2.2 will increase coverage by <.01%.
The diff coverage is 100%.

@@              Coverage Diff               @@
##           release-2.2   #1805      +/-   ##
==============================================
+ Coverage        80.99%     81%   +<.01%     
==============================================
  Files               83      83              
  Lines             6647    6649       +2     
==============================================
+ Hits              5384    5386       +2     
  Misses            1263    1263

Impacted Files	Coverage Δ
mopidy/mpd/protocol/stored_playlists.py	90.9% <100%> (ø)	⬆️
mopidy/mpd/translator.py	95.4% <100%> (+0.1%)	⬆️

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[jodal]

This looked like a no-op to me at first, but this actually encodes the URI as bytes!

[kingosticks]

Yes! It's so tempting to just compare two stringy things called uri but you can't.

[jodal]

data is one small step away from being sent over the network, so it wouldn't be unnatural to keep it as bytes. If we change this to the following, it should work correctly on both Python 2 and 3:

if isinstance(data, compat.text_type):
    data = data.encode('utf-8')
lines = (line for line in data.split(b'\n') if line)  # Note the explicit 'b' here
...

[kingosticks]

OK, sounds sensible. Will update.

[kingosticks]

Hmm but actually, no. This isn't going over the network and don't we want unicode here so that we can just write unicode in the tests?

[kingosticks]

I've just realised I missed the other URI at https://github.com/mopidy/mopidy/blob/develop/mopidy/mpd/translator.py#L113