Fix broken tests due to refactor of PandocUtils.hs/Pandoc.hs

[ajkavanagh]

The tests for links are broken due to a refactor of code from PandocUtils.hs to Pandoc.hs. This was due to the link re-writing code needing access to the Polysemy monad and thus being moved. This now means that the tests will essentially be broken as there (shouldn't be) any code for them to access. If they work, then there is code that is not longer being used.

Main things to do:

• Remove unused code from PandocUtils.hs
• Rewrite the tests to use Pandoc.hs monad equivalent functions, and test using a Polysemy monad.

Tests are broken:

processPandocLinksSpecs
  Should ignore no links at all FAILED [1]

Failures:

  test/Lib/PandocUtilsSpecs.hs:126:20:
  1) processPandocLinksSpecs Should ignore no links at all
       uncaught exception: ErrorCall
       Prelude.undefined
       CallStack (from HasCallStack):
         error, called at libraries/base/GHC/Err.hs:80:14 in base:GHC.Err
         undefined, called at test/Lib/PandocUtilsSpecs.hs:126:20 in main:Lib.PandocUtilsSpecs