Add rainbows for Koto (#14469)

runtime/queries/koto/highlights.scm

@@ -105,7 +105,7 @@
   start: (identifier) @function)
 
 (chain
-  lookup: (identifier) @variable.other.member)
+  (lookup (identifier)) @variable.other.member)
 
 (call
   function: (identifier)) @function

runtime/queries/koto/rainbows.scm

@@ -0,0 +1,11 @@
+[
+  (args)
+  (call_args)
+  (index)
+  (list)
+  (map)
+  (parenthesized)
+  (tuple)
+] @rainbow.scope
+
+["(" ")" "[" "]" "{" "}"] @rainbow.bracket