RFC: Delete functions ggml_backend_graph_compute_async_range and sd_backend_graph_compute_with_eval_callback

[adamjrichter]

There is an unused chain of two functions causing stable-diffusion to get an undefined error symbol when linking against shared external libggml 1.0.0:

ggml_backend_graph_compute_async_range,
sd_backend_graph_compute_with_eval_callback.

Draft pull request #2363 would delete them. It discusses the problem in
more detail, and why it doesn't yet occur when external libggml is a static library.

@leejet, @stduhpf - you are at least the last editors these functions according to "git blame". I know it's an understatemeent, but thank you so much for your work. For these particular function, you or whoever wrote them must have put work into creating them for a reason. So, as a newbie and perhaps passer-by, I want to be careful about just dropping in and proposing to delete code out of the blue. I would welcome guidance from you our anyone else who would care to comment on why these functions should not deleted, and, if so, if it's OK to ifdef them out. Alternatively, if the functions really are going to be used in their current form, perhaps an argument should be made to the libggml developers not to mark that symbol in question (ggml_graph_view) as internal only.

I currently plan to wait until the end of Monday, and, then, if I don't see any comments here or on the diff, I'll convert it to an active pull request.

Thanks in advance for guidance from anyone would care to comment.