Re: speed up a logical replica setup

Dear Euler, hackers,

We fixed some of the comments posted in the thread. We have created it
as top-up patch 0002 and 0003.

0002 patch contains the following changes:
* Add a timeout option for the recovery option, per [1]. The code was
basically ported from pg_ctl.c.
* Reject if the target server is not a standby, per [2]
* Raise FATAL error if --subscriber-conninfo specifies non-local server, per [3]
  (not sure it is really needed, so feel free reject the part.)
* Add check for max_replication_slots and wal_level; as per [4]
* Add -u and -p options; as per [5]
* Addressed comment except 5 and 8 in [6] and comment in [7]

0003 patch contains fix for bug reported in [8].

Feel free to merge parts of 0002 and 0003 if it looks good to you.
Thanks Kuroda-san to make patch 0003 and a part of patch 0002.

[1]: https://www.postgresql.org/message-id/CANhcyEUCt-g4JLQU3Q3ofFk_Vt-Tqh3ZdXoLcpT8fjz9LY_-ww%40mail.gmail.com
[2]: https://www.postgresql.org/message-id/CANhcyEUCt-g4JLQU3Q3ofFk_Vt-Tqh3ZdXoLcpT8fjz9LY_-ww%40mail.gmail.com
[3]:
https://www.postgresql.org/message-id/TY3PR01MB98895BA6C1D72CB8582CACC4F5682%40TY3PR01MB9889.jpnprd01.prod.outlook.com
[4]: https://www.postgresql.org/message-id/CALDaNm098Jkbh%2Bye6zMj9Ro9j1bBe6FfPV80BFbs1%3DpUuTJ07g%40mail.gmail.com
[5]: https://www.postgresql.org/message-id/CAA4eK1JB_ko7a5JMS3WfAn583RadAKCDhiE9JgmfMA8ZZ5xcQw%40mail.gmail.com
[6]:
https://www.postgresql.org/message-id/TY3PR01MB9889C362FF76102C88FA1C29F56F2%40TY3PR01MB9889.jpnprd01.prod.outlook.com
[7]: https://www.postgresql.org/message-id/CANhcyEXjGmryoZPACS_i-joqvcz5e6Zb3u4g38SAy_iSTGhShg%40mail.gmail.com
[8]:
https://www.postgresql.org/message-id/TY3PR01MB9889C5D55206DDD978627D07F5752%40TY3PR01MB9889.jpnprd01.prod.outlook.com

Thanks and regards
Shlok Kyal