Rename stable_mir and rustc_smir

[makai410]

This PR only renames the two crate names.

There is no doubt that we want to rename stable_mir to rustc_public, while it hasn't been discussed yet that what the new name for rustc_smir should be.

This PR proposes a new name for rustc_smir, that is rustc_public_shim, since rustc_smir now is mostly a proxy to do calls to rustc queries and the public API of rustc that is invoked by the rustc_public crate.

However, I don't think that name is good enough. I hope there would be a way better name.

r? @oli-obk

[rustbot]

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

triagebot.toml has been modified, there may have been changes to the review queue.

cc @davidtwco, @wesleywiser