resolve: always align flags to 8th column and print CAA flags

resolve: always align flags to 8th column and print CAA flags

Left-over unknown flags are printed numerically. Otherwise,
it wouldn't be known what bits are remaining without knowning
what the known bits are.

A test case is added to verify the flag printing code:
============== src/resolve/test-data/fake-caa.pkts ==============
google.com. IN CAA   0 issue "symantec.com"
google.com. IN CAA   128 issue "symantec.com"
        -- Flags: critical
google.com. IN CAA   129 issue "symantec.com"
        -- Flags: critical 1
google.com. IN CAA   22 issue "symantec.com"
        -- Flags: 22