[mlir] explicitly delete copy ctor for DialectRegistry and OperationState (#140963)

Both of these classes have fields involving `unique_ptr`s and thus can't
be copied.
Holding a unique_ptr should trigger implicit deletion of the
copy/assignment constructors, however
not when held through a container:

```
struct Foo {  
  explicit Foo();
  std::vector<std::unique_ptr<Bar>> ptr; // Does not implicitly delete its cpy/assign ctors
};
```

This results in a complicated diagnostics when attempting to copy such a
class (it'll point to the
inner implementation of the container), instead of a nicer error message
about `Foo` not being able
to be copied/assigned. Explicitly deleting the ctors provides an
immediate diagnostic about the issue.

Fixes https://github.com/llvm/llvm-project/issues/118388