Drop support for GHC 8.10.7

[lehins]

We are closing in on resolving the issues that prevented us from upgrading the node from using ghc-9 for compilation.

Once we have a successful version of the node that was compiled with ghc-9 happily running on mainnet we can safely drop support for ghc-8.10.7

This ticket captures the task of doing so in ledger and lists all of the things that need to be done, once we do drop that support:

• Remove ghc-8.10 from nix config and from GithubActions CI
• Remove CPP and definition of BaseImpM introduced with Made it possible to use Imp logging in the conformance hook #4796
• Remove conditionals from cabal files:

  if !impl(ghc >=9.2)
    ghc-options: -Wno-name-shadowing

• ...