Prevent duplicate language intent registration

[NeonDaniel]

Update _native_langs to ensure a list of unique full language codes is returned

This enforces full language codes and tosses anything without a region (i.e. en is invalid). Should this try to use default regions from LF?

[codecov]

Codecov Report

Merging #173 (87e914e) into dev (6ceb058) will increase coverage by 2.64%.
The diff coverage is 41.71%.

@@            Coverage Diff             @@
##              dev     #173      +/-   ##
==========================================
+ Coverage   50.35%   52.99%   +2.64%     
==========================================
  Files         119      152      +33     
  Lines       10077     9480     -597     
==========================================
- Hits         5074     5024      -50     
+ Misses       5003     4456     -547     

Impacted Files	Coverage Δ
mycroft/audio/__main__.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/__main__.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/mark1/arduino.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/mark1/eyes.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/mark1/mouth.py	0.00% <0.00%> (ø)
mycroft/client/speech/__main__.py	0.00% <0.00%> (ø)
mycroft/client/speech/hotword_factory.py	0.00% <0.00%> (-88.89%)	⬇️
mycroft/client/speech/service.py	0.00% <0.00%> (ø)
mycroft/client/speech/silence.py	0.00% <0.00%> (-42.86%)	⬇️
mycroft/client/text/__init__.py	0.00% <0.00%> (ø)
... and 128 more

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