dnsmasq: add handling of `filter-rr` to init script

dnsmasq: add handling of `filter-rr` to init script

dnsmasq v2.90 introduced `--filter-rr=<rrtype>[,<rrtype>...]`.

uci config usage:

config dnsmasq
    ...
    option filter_rr 'AAAA,CNAME,NXDOMAIN,SRV,...'

The dnsmasq instance internally builds a linked list of RR to filter
from the individually supplied parameters, so it's harmless to provide
synonyms:

... --filter-A --filter-rr=A ...

See https://forum.openwrt.org/t/resolving-query-type-65-to-local-address-for-ios-clients-in-dnsmasq/179504/23

Tested on: 23.05.2

Signed-off-by: Paul Donald <newtwen+github@gmail.com>
Tested-by: Vladimir Kochkovski <ask@getvladimir.com>
Link: https://github.com/openwrt/openwrt/pull/14975
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>