[llvm] [tools][llc] Add `--save-stats` option (PR #163967)

[Matthias Braun via llvm-commits]

MatzeB wrote:

Reading the existing code you can already do: `--stats-json --info-output-filename=xxxx.json` so do we even need a new option?

(Admittedly the existing one is kinda unintuitively named but oh well...)

https://github.com/llvm/llvm-project/pull/163967