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

[Mehdi Amini via llvm-commits]

https://github.com/joker-eph approved this pull request.

Thanks @fschlimb !

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