The method was only used in unittest where it can be replaced by
UNICHARSET::load_from_file which also simplifies the code.
This allows removing the class InMemoryFilePointer and fixes a TODO.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
* Add abseil library
* Add minimalistic implementation for WriteStringToFile
* Add missing namespace for std::string
Signed-off-by: Stefan Weil <sw@weilnetz.de>