Add Validated.swap

[ceedubs]

Also add unit tests for similar methods on Xor and Coproduct.

[codecov-io]

Current coverage is 85.91%

Merging #731 into master will increase coverage by +0.10% as of 0d1a7ed

@@            master    #731   diff @@
======================================
  Files          162     162       
  Stmts         2249    2250     +1
  Branches        74      74       
  Methods          0       0       
======================================
+ Hit           1930    1933     +3
  Partial          0       0       
+ Missed         319     317     -2

Review entire Coverage Diff as of 0d1a7ed

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[stew]

👍

[adelbertc]

👍