Added parsing BWW messages

[taavit]

Added parsing BWW messages (#54), based on https://gpsd.gitlab.io/gpsd/NMEA.html#_bww_bearing_waypoint_to_waypoint

[elpiel]

All looks good to me, only 2 small requested changes.
Thank you once again for your PR!

[codecov]

Codecov Report

Patch coverage: 81.57% and project coverage change: +0.61 🎉

Comparison is base (b203556) 79.60% compared to head (75c5c1d) 80.22%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #86      +/-   ##
==========================================
+ Coverage   79.60%   80.22%   +0.61%     
==========================================
  Files          30       31       +1     
  Lines        1123     1153      +30     
==========================================
+ Hits          894      925      +31     
+ Misses        229      228       -1     

Impacted Files	Coverage Δ
src/error.rs	5.26% <0.00%> (-0.80%)	⬇️
src/parser.rs	79.13% <0.00%> (+1.82%)	⬆️
src/sentences/mod.rs	0.00% <ø> (ø)
src/parse.rs	72.61% <100.00%> (+0.66%)	⬆️
src/sentences/bww.rs	100.00% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.