[llvm] [mlir] [NFC][mlir][mesh,shard] Fixing misnomers in mesh dialect, renaming 'mesh' dialect to 'shard' (PR #150177)

[Renato Golin via llvm-commits]

https://github.com/rengolin approved this pull request.

Looks good. No objections here or in Discourse, so should be fine.

But still good to wait a few more days, since it's a dialect renaming.

Thanks!

https://github.com/llvm/llvm-project/pull/150177