remove orientation method from supportsOrientation

[tlambert03]

pulling out the orientation getter/setter implementation from the Protocol (didn't belong there)

[codecov]

Codecov Report

Merging #77 (2a5babc) into master (cb0c2f4) will increase coverage by 0.32%.
The diff coverage is 92.30%.

@@            Coverage Diff             @@
##           master      #77      +/-   ##
==========================================
+ Coverage   87.54%   87.87%   +0.32%     
==========================================
  Files          15       15              
  Lines        1614     1616       +2     
==========================================
+ Hits         1413     1420       +7     
+ Misses        201      196       -5     

Impacted Files	Coverage Δ
magicgui/widgets/_bases.py	89.79% <91.66%> (+<0.01%)	⬆️
magicgui/widgets/_protocols.py	76.28% <100.00%> (+1.28%)	⬆️
magicgui/backends/_qtpy/widgets.py	84.45% <0.00%> (+0.84%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cb0c2f4...39b2014. Read the comment docs.