add SRV record support

[purerosefallen]

The port input box would be removed, and server port is typed in after :
The host field supports SRV record parsing, so that players can join servers without a port. The following is an example of SRV record, in which players could join with hostname koishi.momobako.com and it would make the client connect to koishi.momobako.com:7210

In addition, now it also supports format of koishi.momobako.com:7210 with port field blank.

➜  ~ dig _ygopro._tcp.koishi.momobako.com srv                           14:22:46

; <<>> DiG 9.18.1-1ubuntu1.1-Ubuntu <<>> _ygopro._tcp.koishi.momobako.com srv
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7031
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;_ygopro._tcp.koishi.momobako.com. IN	SRV

;; ANSWER SECTION:
_ygopro._tcp.koishi.momobako.com. 60 IN	SRV	0 5 7210 koishi.momobako.com.

;; ADDITIONAL SECTION:
koishi.momobako.com.	60	IN	A	10.198.6.95

;; Query time: 23 msec
;; SERVER: 10.198.7.56#53(10.198.7.56) (UDP)
;; WHEN: Tue Sep 20 14:32:19 CST 2022
;; MSG SIZE  rcvd: 167

[mercury233]

I prefer to keep the port inputbox but accept blank value

[purerosefallen]

I prefer to keep the port inputbox but accept blank value

@mercury233 Players would still have to change text in 2 boxes for switching servers.
After this one, servers should be recognized as a single address, either with address:port format, or single address for SRV record.