refactor(layout): move the remaining types

[joshka]

• alignment -> layout/alignment.rs
• corner -> layout/corner.rs
• direction -> layout/direction.rs
• size -> layout/size.rs

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (659460e) 92.3% compared to head (3ef66b9) 92.3%.

Files	Patch %	Lines
src/layout/size.rs	0.0%	4 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #743   +/-   ##
=====================================
  Coverage   92.3%   92.3%           
=====================================
  Files         52      55    +3     
  Lines      14806   14806           
=====================================
  Hits       13672   13672           
  Misses      1134    1134           

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