Correctly hash inferred types (#8286)

We don't really want to hash the tyInferred container since that'd make
the "real" type and its inferred counterpart produce different hashes
and types for the very same type.

Fixes #8280

tests/concepts/t8280.nim

@@ -0,0 +1,16 @@
+discard """
+  output: "()"
+"""
+
+type
+  Iterable[T] = concept x
+    for elem in x:
+      elem is T
+
+proc max[A](iter: Iterable[A]): A = 
+  discard
+
+type
+  MyType = object
+
+echo max(@[MyType()])