Implement the is operator for the new static and typedesc type classes

This also makes the first baby steps towards a sound treatment of
higher-order kinds (type type int).

Adds test cases showcasing the new features.

* Also fixes breakage after the rebase

tests/parser/ttypeclasses.nim

@@ -1,17 +1,42 @@
-discard """
-    action: run
-"""
-
 type
     R = ref
     V = var
     D = distinct
     P = ptr
+    T = type
+    S = static
+    OBJ = object
+    TPL = tuple
+    SEQ = seq
 
+var i: int
 var x: ref int
 var y: distinct int
 var z: ptr int
+const C = @[1, 2, 3]
+
+static:
+  assert x is ref
+  assert y is distinct
+  assert z is ptr
+  assert C is static
+  assert C[1] is static[int]
+  assert C[0] is static[SomeInteger]
+  assert C isnot static[string]
+  assert C is SEQ|OBJ
+  assert C isnot OBJ|TPL
+  assert int is int
+  assert int is T
+  assert int is SomeInteger
+  assert seq[int] is type
+  assert seq[int] is type[seq]
+  assert seq[int] isnot type[seq[float]]
+  assert i isnot type[int]
+  assert type(i) is type[int]
+  assert x isnot T
+  assert y isnot S
+  assert z isnot enum
+  assert x isnot object
+  assert y isnot tuple
+  assert z isnot seq
 
-doAssert x is ref
-doAssert y is distinct
-doAssert z is ptr