Add tasks for all the new languages

Task/Arrays/Pony/arrays.pony

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+var numbers = Array[I32](16) // creating array of 32-bit ints with initial allocation for 16 elements
+numbers.push(10) // add value 10 to the end of array, extending the underlying memory if needed
+try
+  let x = numbers(0) // fetch the first element of array. index starts at 0
+  Fact(x == 10)      // try block is needed, because both lines inside it can throw exception
+end
+
+var other: Array[U64] = [10, 20, 30] // array literal
+let s = other.size() // return the number of elements in array
+try
+  Fact(s == 3)  // size of array 'other' is 3
+  other(1) = 40 // 'other' now is [10, 40, 30]
+end