Function deltachat::imap::build_sequence_sets

fn build_sequence_sets(uids: &[u32]) -> Result<Vec<(Vec<u32>, String)>>

Builds a list of sequence/uid sets. The returned sets have each no more than around 1000 characters because according to https://tools.ietf.org/html/rfc2683#section-3.2.1.5 command lines should not be much more than 1000 chars (servers should allow at least 8000 chars)