feat: add sample(list) and sample(list, count) methods to Random class with two sampling algorithms

test/random/sample_count_one.wren

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+import "random" for Random
+
+var random = Random.new(12345)
+
+// Single element list.
+System.print(random.sample(["single"], 1)) // expect: [single]
+
+// Should choose all elements with roughly equal probability.
+var list = ["a", "b", "c", "d", "e"]
+var histogram = {}
+for (i in 1..5000) {
+  var sample = random.sample(list, 1)
+
+  var string = sample.toString
+  if (!histogram.containsKey(string)) histogram[string] = 0
+  histogram[string] = histogram[string] + 1
+}
+
+System.print(histogram.count) // expect: 5
+for (key in histogram.keys) {
+  var error = (histogram[key] / (5000 / list.count) - 1).abs
+  if (error > 0.1) System.print("!!! %(error)")
+}