[mlir] Require explicit casts when using TypedValue

[mlir] Require explicit casts when using TypedValue

Currently `TypedValue` can be constructed directly from `Value`, hiding
errors that could be caught at compile time. For example the following
will compile, but crash/assert at runtime:
```
void foo(TypedValue<IntegerType>);
void bar(TypedValue<FloatType> v) {
  foo(v);
}
```

This change removes the constructors and replaces them with explicit
llvm casts.

Depends on D142852

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D142855