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.

hypsrc-test/ref/src/CPP.html

@@ -24,8 +24,12 @@
       >module</span
       ><span
       > </span
-      ><span class="hs-identifier"
-      >CPP</span
+      ><span class="annot"
+      ><a href="CPP.html"
+	><span class="hs-identifier"
+	  >CPP</span
+	  ></a
+	></span
       ><span
       > </span
       ><span class="hs-keyword"