Introduce the calculate_affected_clustering_ranges() function to
calculate the smallest subject of affected clustering ranges that we
need to query for.
The update_requires_read_before_write() function checks whether
a view is potentially affected by the base update.
The patch also cleans up the may_be_affected_by() function.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>