feat: execute fixed arrays and indexed access

programs/array_sum.hon

@@ -0,0 +1,12 @@
+main proc() int {
+    values [4]mut i64 := [1, 2, 3, 4]
+    values[2] = 10
+
+    total := 0
+    count usize :: 4
+    for 0..count |index| {
+        total = total + values[index]
+    }
+
+    return total
+}