Fix compiler crash in PatternMatcher

My understanding is that the test case in i24504 is expected to take
this branch:
https://github.com/scala/scala3/blob/0470ec1ff46a822ca58e204587fb67d56004623a/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala#L420
where we the info is comming from
https://github.com/scala/scala3/blob/0470ec1ff46a822ca58e204587fb67d56004623a/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala#L118-L124
that has called `dropNamedTuple`
https://github.com/scala/scala3/blob/0470ec1ff46a822ca58e204587fb67d56004623a/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala#L113-L115

the problem is that under this case the type will be `NamedTuple.From`
for which `isNamedTupleType` returns false. Which means that the
returned type will not be a `NonEmptyTupleType`.

The fix in this mr adds a `normalized.dealias` call in
`isNormalizedTupleType` which brings it inline with
`stripNormalizedTupleType`. But seems feasible that a better fix could
be that `NamedTuple.From` should have already been removed earlier. But
it not clear to me if that possible.

fixes: i24504

Author: eejbyfeldt

compiler/src/dotty/tools/dotc/core/TypeUtils.scala

@@ -156,7 +156,7 @@ class TypeUtils:
       else
         self
 
-    def isNamedTupleType(using Context): Boolean = self match
+    def isNamedTupleType(using Context): Boolean = self.normalized.dealias match
       case defn.NamedTuple(_, _) => true
       case _ => false
 

tests/pos/i24504.scala

@@ -0,0 +1,12 @@
+object Unpack {
+  trait Expr[T] {
+    type Fields = NamedTuple.From[T]
+  }
+  final case class Pair(a: Int, b: Int)
+  def unapply(e: Expr[Pair]): e.Fields = ???
+
+  val x: Expr[Pair] = ???
+  x match {
+    case Unpack(_, _) => ???
+  }
+}