Add tasks for all the new languages

Task/Catamorphism/Nim/catamorphism.nim

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+import sequtils
+
+block:
+  let
+    numbers = @[5, 9, 11]
+    addition = foldl(numbers, a + b)
+    substraction = foldl(numbers, a - b)
+    multiplication = foldl(numbers, a * b)
+    words = @["nim", "rod", "is", "cool"]
+    concatenation = foldl(words, a & b)
+
+block:
+  let
+    numbers = @[5, 9, 11]
+    addition = foldr(numbers, a + b)
+    substraction = foldr(numbers, a - b)
+    multiplication = foldr(numbers, a * b)
+    words = @["nim", "rod", "is", "cool"]
+    concatenation = foldr(words, a & b)