Support lexicographically sorting of Strings

[cmelchior]

We had a handful of questions now around our support for lexicographically sorting of strings. More commonly people want to do something like realm.where(Person.class).greaterThan("name", "abc").findAll().

One example: https://stackoverflow.com/questions/44581878/realm-string-greaterthan

Supporting this will be trivial if/when Realm Core adds support for it: https://github.com/realm/realm-core/issues/2786

[caeduk]

@cmelchior @bmunkholm any news on this?

[caeduk]

was also requested here https://github.com/realm/realm-java/issues/4283

[caeduk]

@cmelchior bump