[llvm] [mlir] [mlir][core] Add an MLIR "pattern catalog" generator (PR #146228)

[Jeremy Kun via llvm-commits]

j2kun wrote:

Using ToolSubst I modified the PR to no longer use file writing and/or the mutex. It's quite simple now, and the last two steps before this PR can feasibly be merged are:

1. Add a test that ensures the catalog output is printed.
2. Ensure the conversion rewriter patterns are working (it seems `replaceOp` on conversion pattern rewriter is not notifying the listener)

https://github.com/llvm/llvm-project/pull/146228