In a bunch of cases, this actually ends up simplifying the code as
to_number will handle something such as:
```
Optional<I> opt;
if constexpr (IsSigned<I>)
opt = view.to_int<I>();
else
opt = view.to_uint<I>();
```
For us.
The main goal here however is to have a single generic number conversion
API between all of the String classes.
This will effectively allow us to use C++ code as an input for the
compiler. This would be useful for testing, since otherwise we would
have had to specify tests as a spec-like XML, which is not exactly the
most developer-friendly experience.