feat(Tuple): Stub for a template type

This adds the target initial definition of a homogeneous Tuple<T>
  type, and just enough processing that the type can be defined and
  non-template methods that deal with the generic base type Tuple can
  be called. Still has no actual template instantiation.

test/tuple/_native.mjs

@@ -0,0 +1,9 @@
+import assert from 'assert'
+import math from '../../src/pocomath.mjs'
+
+describe('tuple', () => {
+   it('can be created and provide its length', () => {
+      assert.strictEqual(math.length(math.tuple(3,5.2,2n)), 3)
+   })
+
+})