German sharp S uppercase mapping

[Dominikus Dittes Scherkl]

Am 26.11.24 um 17:59 schrieb Peter Constable via Unicode:
> The case pair stability requirement applies to default data. Conforming applications can still tailor case mapping behaviour use language-specific overrides. However, the default case pairs as defined in the SpecialCasing.txt and UnicodeData.txt files must remain stable so as not to break existing implementations of file systems or other identifier systems that depend on the default case pairs.

I think nowadays ẞ is preferred over SS, and _especially_ the default
should be changed to use this, because if a text is automatically
processed by e.g. functions like toUpper(), the old form is not
invertible. If the old form is intended, it is very easy to replace
every occurrence of ẞ by SS, but in the other direction not every SS has
to be replaced by ẞ, making it a time consuming manual task to change back.
And this problem was the reason why ẞ was introduced at all. After this
introduction the main reason to use SS was that it was not officially
allowed to use ẞ until 2017. Now the only reason to use SS as uppercase
would be if old equipment is used, that doesn't provide the new letter.
Luckily that is vanishing.