Increase length of the RBAC role names

Currently we create our role names internally using `ShortCapitalString` which allows us to have at most 12 chars in the name. The problem is that any attempt to create an admin role for any of our roles (for example, create the `GER_INJECTOR_ADMIN`) will result in an error: name will be too long. So we should either change the way we construct the role name, or somehow update the `ShortCapitalString`, for example, making its `MAX_LENGTH` a constant parameter:
```rust
pub(crate) struct ShortCapitalString(String);
```

_Originally posted by @Fumuran in https://github.com/0xMiden/protocol/issues/3130#issuecomment-4925789869_