Switch Hover from MarkedString to MarkupContent (#1473)

MarkedString is deprecated in LSP (both the protocol itself and the
Haskell library) so we should move away from it.

src/Development/IDE/Functions/AtPoint.hs

@@ -58,7 +58,7 @@ atPoint tcs srcSpans pos = do
     SpanInfo{..} <- listToMaybe $ orderSpans $ spansAtPoint pos srcSpans
     ty <- spaninfoType
     let mbName  = getNameM spaninfoSource
-        mbDefinedAt = HoverHeading . ("Defined " <>) . T.pack . showSDocUnsafe . pprNameDefnLoc <$> mbName
+        mbDefinedAt = fmap (\name -> HoverMarkdown $ "**Defined " <> T.pack (showSDocUnsafe $ pprNameDefnLoc name) <> "**\n") mbName
         mbDocs  = fmap (\name -> getDocumentation name tcs) mbName
         docInfo = maybe [] (map HoverMarkdown . docHeaders) mbDocs
         range = Range

src/Development/IDE/Types/LSP.hs

@@ -16,9 +16,7 @@ import Development.IDE.Types.Diagnostics
 
 -- | Different types of content we can show on hover.
 data HoverText
-    = HoverHeading !T.Text
-      -- ^ A header that explains the content below it.
-    | HoverDamlCode !T.Text
+    = HoverDamlCode !T.Text
       -- ^ Highlighted DAML-Code
     | HoverMarkdown !T.Text
       -- ^ Markdown text.
@@ -26,7 +24,6 @@ data HoverText
 
 getHoverTextContent :: HoverText -> T.Text
 getHoverTextContent = \case
-    HoverHeading t -> t
     HoverDamlCode t -> t
     HoverMarkdown t -> t