fixes generic types sink T cannot be inferred for passed arguments (#24761)

Otherwise, `sink T` is kept as it is. This PR treats sink types as its
base types for the arguments. So the concept would match both cases

Required by https://github.com/nim-lang/Nim/pull/24724

tests/concepts/tconcept_old.nim

@@ -0,0 +1,18 @@
+type
+  Map[K, V] = concept m, var mvar
+    m[K] is V
+    m[K] = V
+
+  Table[K, V] = object
+
+proc `[]=`[K, V](m: Table[K, V], x: sink K, y: sink V) =
+  let s = x
+
+proc `[]`[K, V](m: Table[K, V], x: sink K): V =
+  let s = x
+
+proc bat[K, V](x: Map[K, V]): V =
+  let m = x
+
+var s = Table[int, string]()
+discard bat(s)