[inductor] Refactor and optimize allocation calls (#111117)
This splits out changes from
https://github.com/pytorch/pytorch/pull/102625 to make things easier to
review.
This diff creates a `make_allocation()` method that extracts the logic
from `make_buffer_allocation()` while allowing us to allocate non-buffer
objects. In particular, we will use this to allocate memory pools during
memory planning.
This diff also includes a small optimization -- if the desired
allocation is contiguous, then we emit a call to `empty()` instead of
`empty_strided()` with its superfluous stride argument.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111117
Approved by: https://github.com/jansel
