Pull request: 3184 disable private ptr

Merge in DNS/adguard-home from 3184-disable-ptr to master

Updates #3184.

Squashed commit of the following:

commit b78ac2eeb1b408586808ddbd1c87107f373b11b0
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Wed May 26 17:20:34 2021 +0300

    all: rename dns config field

commit 36512134822a5f6b8b296ccbd7e7d5a9b8e87f26
Author: Ildar Kamalov <ik@adguard.com>
Date:   Wed May 26 15:55:44 2021 +0300

    client: handle local ips rdns

commit 9a691830d45db93e078332d85bc0efa7dc7b6ac6
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Wed May 26 14:43:13 2021 +0300

    all: imp naming

commit 771b7a3d5d25f91408dd97ba3287efb641028ccf
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Wed May 26 14:24:38 2021 +0300

    all: imp docs, code

commit be960893e8bbb7375a944ca0345b50c857a2d7cf
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Wed May 26 13:23:56 2021 +0300

    all: imp docs & log changes

commit 4e645a520f6bb584ef951435ee833ad30769af98
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Wed May 26 12:49:44 2021 +0300

    all: add the field into structs

commit 22b5b6163f086560a3189234532ba877be7ba940
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue May 25 15:10:31 2021 +0300

    dnsforward: entitle lock, imp code

openapi/CHANGELOG.md

@@ -2,11 +2,18 @@
 
 <!-- TODO(a.garipov): Reformat in accordance with the KeepAChangelog spec. -->
 
+## v0.107: API changes
+
+### The field `"use_private_ptr_resolvers"` in DNS configuration
+
+* The new optional field  `"use_private_ptr_resolvers"` of `"DNSConfig"`
+  specifies if the DNS server should use `"local_ptr_upstreams"` at all.
+
 ## v0.106: API changes
 
 ### The field `"supported_tags"` in `GET /control/clients`
 
-* Prefiously undocumented field `"supported_tags"` in the response is now
+* Previously undocumented field `"supported_tags"` in the response is now
   documented.
 
 ### The field `"whois_info"` in `GET /control/clients`

openapi/openapi.yaml

@@ -1300,6 +1300,8 @@
           - ''
           - 'parallel'
           - 'fastest_addr'
+        'use_private_ptr_resolvers':
+          'type': 'boolean'
         'resolve_clients':
           'type': 'boolean'
         'local_ptr_upstreams':