Mega-issue: switch from test-framework to tasty

[RyanGlScott]

Per the test-framework README and haskell/test-framework#62, the test-framework series of packages is no longer actively developed, and test-framework users are encouraged to switch to a more actively developed test framework. The tasty library has an API very similar to that of test-framework, so I propose that lens (as well as other projects in the Kmettiverse) switch from test-framework to tasty.

Packages that will need to be updated:

• either (Migrate from test-framework to tasty either#68)
• ersatz (Migrate from test-framework to tasty ersatz#100)
• exceptions (Migrate from test-framework to tasty exceptions#101)
• half (Migrate from test-framework to tasty half#42)
• lens (Migrate from test-framework to tasty #1091)
• linear (Migrate from test-framework to tasty linear#185)
• haskell-compat/foldable1-classes-compat (Migrate from test-framework to tasty haskell-compat/foldable1-classes-compat#23)