[Support][Casting] Add predicates for `isa*` functions (#83753)

Expose function objects that call into `llvm::isa` and
`llvm::isa_and_present`, such that these type checks can be used as
predicates in generic algorithms.

Before this change, `llvm::isa*` functions cannot be easily used without
knowing both the argument type and the checked types, which leads to
them being wrapped in lambdas. For example:
```c++
llvm::all_of(myTypes,
             [](auto type) { return llvm::isa<VectorType>(type); });
```

With this PR the example above becomes:
```c++
llvm::all_of(myTypes, llvm::IsaPred<VectorType>);
```

As an alternative solution, I considered redefining `isa*` as function
objects, but I decided against doing that because it would create
asymmetry with other cast *functions* and could break code that depends
on them being actual functions.