fix ghc #24493, with module name introduced in hieAst

The accompanies haddoc PR with GHC PR ghc!12153 (closed)

Two things have been done:

1. Link is introduced to every X in module X where, since we introduce the module name to HieAst,
2. {-# LINE 4 "hypsrc-test/src/PositionPragmas.hs" #-} is added before the module PositionPragmas where in hypsrc-test/ref/src/PositionPragmas.html. It ensures only a single hieAst for file hypsrc-test/src/PositionPragmas.hs is generated.