Added std/effecttraits.nim (#15462)

tests/macros/tgetraiseslist.nim

@@ -0,0 +1,22 @@
+discard """
+  nimout: '''##[ValueError, Gen[string]]##'''
+"""
+
+import macros
+import std / effecttraits
+
+type
+  Gen[T] = object of CatchableError
+    x: T
+
+macro m(call: typed): untyped =
+  echo "##", repr getRaisesList(call), "##"
+  result = call
+
+proc r(inp: int) =
+  if inp == 0:
+    raise newException(ValueError, "bah")
+  elif inp == 1:
+    raise newException(Gen[string], "bahB")
+
+m r(2)