<random>: Implement modified ziggurat algorithm for normal_distribution

[statementreply]

This PR implements modified ziggurat algorithm for normal_distribution, based on McFarland, C. D. (2015). A modified ziggurat algorithm for generating exponentially and normally distributed pseudorandom numbers.

The main differences between this PR and the paper:

• The layers are moved upwards to reduce the area of non-rectangular regions, creating a bottommost layer of which the size of the rectangular region is smaller than 1/N.
• Different criteria are used for the always sampled and always rejected regions of ziggurat overhangs.

Benchmark results for x64 on Intel Core i5-13600KF:

Benchmark	Time	Speed Up
BM_Generator<std::mt19937_64>	3.39 ns
BM_Generator<b_r::mt19937_64>	2.52 ns
BM_Distribution<std::mt19937_64, std_old::normal_distribution<double>>	8.91 ns	1.00
BM_Distribution<std::mt19937_64, std_new::normal_distribution<double>>	4.52 ns	1.97
BM_Distribution<std::mt19937_64, boost_r::normal_distribution<double>>	5.48 ns	1.63
BM_Distribution<b_r::mt19937_64, boost_r::normal_distribution<double>>	4.50 ns	1.98
BM_Generator<std::mt19937>	3.00 ns
BM_Generator<b_r::mt19937>	2.12 ns
BM_Distribution<std::mt19937, std_old::normal_distribution<float>>	8.12 ns	1.00
BM_Distribution<std::mt19937, std_new::normal_distribution<float>>	4.41 ns	1.84
BM_Distribution<std::mt19937, boost_r::normal_distribution<float>>	5.28 ns	1.54
BM_Distribution<b_r::mt19937, boost_r::normal_distribution<float>>	4.33 ns	1.88

Removed tests\GH_004618_normal_distribution_avoids_resets which became moot.

Fixes #1003.

[frederick-vs-ja]

Can we remove _Signed is it's always true?

Suggested change

	template <class _Ty, class _Uty, bool _Signed, int _Lx>
	template <class _Ty, class _Uty, int _Lx>

[statementreply]

It's reserved for exponential_distribution, where _Signed would be false.

[frederick-vs-ja]

Suggested change

	using _Xtype = conditional_t<_Signed, make_signed_t<_Uty>, _Uty>;
	using _Xtype = make_signed_t<_Uty>;

Also, would it be better to rename it to _Sint_type?

[frederick-vs-ja]

Let's avoid numeric_limits.

Suggested change

	static constexpr _Ty _Width_scale = (_Signed ? _Ty{1} : _Ty{2}) * _Ty{(numeric_limits<_Uty>::max)() / 2u + 1u};
	static constexpr _Ty _Width_scale = _Ty{static_cast<_Uty>(-1) / 2u + 1u};

[MattStephanson]

The upper bits of _Xbits could be used on the first iteration. Also for the tail, below.