[client] Support disable search domain for custom zones (#4826)

Two new boolean flags, SearchDomainDisabled and SkipPTRProcess, are added to CustomZone and its protobuf; they are propagated through the engine to DNS host logic. Host matching now uses SearchDomainDisabled directly, and PTR collection skips zones with SkipPTRProcess; reverse zones are initialized with SearchDomainDisabled: true.

dns/dns.go

@@ -45,6 +45,10 @@ type CustomZone struct {
 	Domain string
 	// Records custom zone records
 	Records []SimpleRecord
+	// SearchDomainDisabled indicates whether to add match domains to a search domains list or not
+	SearchDomainDisabled bool
+	// SkipPTRProcess indicates whether a client should process PTR records from custom zones
+	SkipPTRProcess bool
 }
 
 // SimpleRecord provides a simple DNS record specification for CNAME, A and AAAA records