Tidy up Do Expansion implimentation/Kill `GHC.Types.Basic.Origin`

This ticket tracks various tidying up tasks for HsExpansion

Here are some ideas:

1. Get rid Origin to beautify and stream line the Generated code vs FromSource Code meta-data. See discussion here: !10140 (comment 535779)

The current design depends on GHC.Types.Basic.Origin and also GHC.Types.SrcLoc.GenLocated to figure out whether a source code's origin is user written or not. The objective is that we should only be using one thing to identify the source codes origin. The current tcExpr already uses GHC.Types.SrcLoc.GenLocated to identify the src origin using isGeneratedCode :: TcRn Bool and we would be able to reuse that functionality rather than depending on GHC.Types.Basic.Origin.

2. Kill GenReason in GHC.Types.Basic.Origin and clean up smelly code like this one in GHC.HstoCore.Match.matchWrapper

= do { dflags <- getDynFlags
     ; locn <- getSrcSpanDs
     ; let matches
     = if any (is_pat_syn_match origin) matches'
          then filter (non_gen_wc origin) matches'
          -- filter out the wild pattern fail alternatives
          -- which have a do expansion origin
          -- They generate spurious overlapping warnings
          -- Due to pattern synonyms treated as refutable patterns
          -- See Part 1's Wrinkle 1 in Note [Expanding HsDo with XXExprGhcRn] in GHC.Tc.Gen.Do