This change completes handling for all ARIA properties defined in the
current ARIA spec — by adding handling for the following properties:
- aria-braillelabel
- aria-brailleroledescription
- aria-colindextext
- aria-description
- aria-rowindextext
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.