MM-56876: Redis: first introduction (#27752)

```release-note
NONE
```

---------

Co-authored-by: Jesús Espino <jespinog@gmail.com>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/platform/services/cache/cache.go

@@ -34,6 +34,8 @@ type Cache interface {
 	// Return ErrKeyNotFound if the key is missing from the cache
 	Get(key string, value any) error
 
+	GetMulti(keys []string, values []any) []error
+
 	// Remove deletes the value for a given key.
 	Remove(key string) error