Enforce UTF-8 encoding on reading and writing files

[Jimbo4350]

We were experiencing testing failures on Windows due to GHC 8.10.7's readFile not using UTF-8 by default. This caused golden file comparison errors when Unicode characters were present. For example:

478 ┃ testAllErrorMessages_
      479 ┃   :: forall a
      480 ┃    . (HasCallStack, Error a)
      481 ┃   => String
      482 ┃   -- ^ module name
      483 ┃   -> String
      484 ┃   -- ^ type name
      485 ┃   -> [(String, a)]
      486 ┃   -- ^ list of constructor names and values
      487 ┃   -> TestTree
      488 ┃ testAllErrorMessages_ = ErrorMessage.testAllErrorMessages_ goldenFilesPath
          ┃ │ Incorrect error message in golden file
          ┃ │ Reading file: test/cardano-api-golden/files/golden/errors\Cardano.Api.Fees.ScriptExecutionError\ScriptErrorEvaluationFailed.txt
          ┃ │ Golden test failed against the golden file.
          ┃ │ To recreate golden file, run with RECREATE_GOLDEN_FILES=1.
          ┃ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
          ┃ │ 37c37
          ┃ │ <      Valid range: (-∞ , +∞)
          ┃ │ ---
          ┃ │ >      Valid range: (-Γê₧ , +Γê₧)

[carbolymer]

evalIO is needed for proper reporting of IO exceptions

Suggested change

	liftIO $ IO.withFile filePath IO.ReadMode $ \handle -> do
	H.evalIO $ IO.withFile filePath IO.ReadMode $ \handle -> do

Why this change is only in those two places ? I think we should use utf8 in all functions using string / text when accessing files:
appendFile, textWriteFile, textReadFile, fileContains

[newhoggy]

I think you are right. However, it makes sense to accept this PR as an improvement to the library and do the other fixes in a future PR.

[carbolymer]

do the other fixes in a future PR

Fine but let's do them before making a new release... And the version of hedgehog-extras with this change was tagged already. Can we try to limit technical debt we're introducing?

Or at least put an effort into making technical debt manageable and traceable by creating follow-up tickets/prs?

Recommend further PRs