Adds limit and offset clauses for Delete and Update builders in SQLite

[belchior]

The clauses limit and offset are behind a flag at SQLite, more info.

Basic API

#[cfg(feature = "sqlite")]
{
  use sql_query_builder as sql;
  
  let delete = sql::Delete::new()
    .limit("100")
    .offset("50");
    
  let expected = "LIMIT 100 OFFSET 50";
  assert_eq!(expected, delete.as_string());
}

References

• https://sqlite.org/lang_update.html
• https://sqlite.org/lang_delete.html