[ESIMD] Improve simd::replicate API

[DenisBakhvalov]

This patch deprecates two error-prone versions of simd::replicate API:

• auto v0_rep = v0.replicate<2, 4, 2>(1);
• auto v0_rep = v0.replicate<2, 4, 2, 2>(1);

To replace them, we introduce a struct of compile-time arguments, which user can fill with:

  simd<int, 8> v0(0, 1);
  using v0_type = decltype(v0);
  using RepOpts = typename v0_type::ReplicateOptsBuilder<2>::
                                    template vstride<4>::
                                    template width<2>::
                                    template hstride<2>::type;
  auto v0_rep = v0.replicate<RepOpts>(1);

[DenisBakhvalov]

I think we can keep the first two (simple) versions of simd::replicate API:

• auto v0_rep = v0.replicate<1>();
• auto v0_rep = v0.replicate<4, 2>(2);

Otherwise, it becomes too much of a boilerplate to type.
Also, the version with two template parameters is tricky. The second template parameter sets two arguments at the same time: Width and Vstride.

[DenisBakhvalov]

We discussed that with @rolandschulz and @kbobrovs and agreed that this way would be too verbose.
The alternative that we agreed to provide is to reflect the order of the template arguments in the name of the API:

template <int Rep> replicate
template <int Rep, int W> replicate_w
template <int Rep, int VS, int W>replicate_vs_w
template <int Rep, int VS, int W, int HS> replicate_vs_w_hs

[DenisBakhvalov]

I updated the PR according to what we agreed.
@kbobrovs, please review.

llvm-test-suite patch is in progress.

[kbobrovs]

@DenisBakhvalov, please add E2E test to llvm-test-suite too.

[kbobrovs]

@rolandschulz, we've got informal approval from you when discussing it, but a formal one here from you would be appreciated.

[kbobrovs]

@rolandschulz, merging this one - let us know if you have comments.