[llvm] [mlir] [mlir] Mark `isa/dyn_cast/cast/...` member functions deprecated. (PR #90413)

[Daniel Chen via llvm-commits]

DanielCChen wrote:

It seems this PR causes build failure as
```
llvm-project/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp:148:26: error: 'dyn_cast' is deprecated: Use mlir::dyn_cast<U>() instead [-Werror,-Wdeprecated-declarations]
    if (auto funcLoc = l.dyn_cast<mlir::FileLineColLoc>())
                         ^

```

There are also quite a lot `warning` on top of the failures. @chsigg 

https://github.com/llvm/llvm-project/pull/90413