remotecache: support SSL with redis (#18511)

* update go-redis lib from v2 -> v5
* add ssl option to the redis connection string
fixes #18498

go.mod

@@ -52,7 +52,7 @@ require (
 	github.com/onsi/gomega v1.5.0 // indirect
 	github.com/opentracing/opentracing-go v1.1.0
 	github.com/patrickmn/go-cache v2.1.0+incompatible
-	github.com/pkg/errors v0.8.1 // indirect
+	github.com/pkg/errors v0.8.1
 	github.com/prometheus/client_golang v0.9.2
 	github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90
 	github.com/prometheus/common v0.2.0
@@ -80,12 +80,11 @@ require (
 	golang.org/x/xerrors v0.0.0-20190410155217-1f06c39b4373
 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect
 	gopkg.in/asn1-ber.v1 v1.0.0-20181015200546-f715ec2f112d // indirect
-	gopkg.in/bufio.v1 v1.0.0-20140618132640-567b2bfa514e // indirect
 	gopkg.in/ini.v1 v1.42.0
 	gopkg.in/ldap.v3 v3.0.2
 	gopkg.in/macaron.v1 v1.3.2
 	gopkg.in/mail.v2 v2.3.1
-	gopkg.in/redis.v2 v2.3.2
+	gopkg.in/redis.v5 v5.2.9
 	gopkg.in/square/go-jose.v2 v2.3.0
 	gopkg.in/yaml.v2 v2.2.2
 )