WireGuard outbound: Add remoteDNS & honor TTL (#6620)

Closes https://github.com/XTLS/Xray-core/pull/6569#issuecomment-5263789755

Fixes https://github.com/XTLS/Xray-core/issues/6567#issuecomment-5150957597

---------

Co-authored-by: LagPixelLOL <2282688304@qq.com>

infra/conf/wireguard.go

@@ -66,6 +66,7 @@ type WireGuardConfig struct {
 	MTU            int32                  `json:"mtu"`
 	Reserved       []byte                 `json:"reserved"`
 	DomainStrategy string                 `json:"domainStrategy"`
+	DNS            []string               `json:"remoteDNS"`
 }
 
 func (c *WireGuardConfig) Build() (proto.Message, error) {
@@ -141,6 +142,7 @@ func (c *WireGuardConfig) Build() (proto.Message, error) {
 
 	config.IsClient = c.IsClient
 	config.NoKernelTun = c.NoKernelTun
+	config.DNS = c.DNS
 
 	return config, nil
 }