PyTorch 2.1.2 Release, bug fix release

This release is meant to fix the following issues (regressions / silent correctness):

• Fix crashes for float16 empty tensors (#115183)
• Fix MPS memory corruption when working with tensor slices (#114838)
• Fix crashes during Conv backward pass on MPS devices (#113398)
• Partially fix nn.Linear behavior on AArch64 platform (#110150)
• Fix cosine_similarity for tensors of different sizes (#109363)
• Package missing headers needed for extension development (#113055)
• Improve error handling of torch.set_num_threads (#113684)
• Fix profiling traces generation (#113763)

The Cherry pick tracker #113962 contains all relevant pull requests related to this release as well as links to related issues.