Backport "Show documentation for value forwarders in completions" to LTS (#20788)

Backports #19200 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

presentation-compiler/src/main/dotty/tools/pc/CompletionItemResolver.scala

@@ -69,6 +69,8 @@ object CompletionItemResolver extends ItemResolver:
               fullDocstring(tr.symbol, search)
             case _ =>
               ""
+        else if gsym.isTerm && gsym.info.typeSymbol.is(Module) then
+          fullDocstring(gsym.info.typeSymbol.companion, search)
         else ""
       else gsymDoc
     else

presentation-compiler/src/main/dotty/tools/pc/completions/CompletionValue.scala

@@ -83,6 +83,8 @@ object CompletionValue:
           s"${labelWithSuffix(printer)} -${description(printer)}"
         else s"${labelWithSuffix(printer)}${description(printer)}"
       else if symbol.isType then labelWithSuffix(printer)
+      else if symbol.isTerm && symbol.info.typeSymbol.is(Module) then
+        s"${label}${description(printer)}"
       else s"$label: ${description(printer)}"
 
     private def labelWithSuffix(printer: ShortenedTypePrinter)(using Context): String =