Infer required keys in return of maps:with when open shape has dynami…

…c() keys

Summary: Based on internal discussions, we decided that `#{dynamic() => dynamic()} <: #{a := dynamic()}` should hold. On this diff I'm special casing `maps:with` custom typing to produce required keys when that happens.

Reviewed By: VLanvin

Differential Revision: D66828846

fbshipit-source-id: 6aae2c9dc09004387f9056a0ac71a4f11b672a46

eqwalizer/src/main/scala/com/whatsapp/eqwalizer/tc/ElabApplyCustom.scala

@@ -521,6 +521,7 @@ class ElabApplyCustom(pipelineContext: PipelineContext) {
           val props = keysToKeep.flatMap { key =>
             mapTy.props.get(key) match {
               case Some(vProp)                                           => Some(key -> vProp)
+              case None if mapTy.kType == DynamicType                    => Some(key -> Prop(true, mapTy.vType))
               case None if subtype.subType(Key.asType(key), mapTy.kType) => Some(key -> Prop(false, mapTy.vType))
               case None                                                  => None
             }