feat(Tuples): Add Tuples.Flatten

[airismadeupofair]

Hello,

Firstly thank you for this very powerful library 👍.
but i found a small limitation within the Tuples namespace
there was no flatten. so i made one.

it can handle depths way over 20. and can handle over 1000 items at once.
it can even handle spreads properly including the array of a tuple spread case.

these are some of the test cases that passed on github actions.

// hundred brackets
    type res1 = Call<Tuples.Flatten, [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[1]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]], [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[...string[]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]], 100>
    //   ^?
    type res2 = Call<Tuples.Flatten,[[1, 2],[[[3]]],[],[4,[5,[6,[...string[],7]]]],[[8],9],...[10, 11][]],4>;
    //   ^?

    type tes1 = Expect<Equal<res1, [1, ...string[]]>>
    
    type tes2 = Expect<Equal<res2, [1, 2, 3, 4, 5, 6, ...(string | 7 | 8 | 9 | 10 | 11)[]]>>

note:

the implementation is 94 KB. it is large but almost 84KB is generated by scripts. however this is the cost for optimisation as standard recursion for the main utilites that are used by the Flatten caused the instantiation count to explode.