[#165] Support streaming listing

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

api/layer/cache.go

@@ -1,6 +1,8 @@
 package layer
 
 import (
+	"context"
+
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/cache"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/logs"
@@ -10,7 +12,15 @@ import (
 	"go.uber.org/zap"
 )
 
+type TestCacheValue struct {
+	Next     *data.ObjectInfo
+	Stream   LatestVersionsByPrefixStream
+	NamesMap map[string]struct{}
+	Context  context.Context
+}
+
 type Cache struct {
+	testCache   map[string]TestCacheValue
 	logger      *zap.Logger
 	listsCache  *cache.ObjectsListCache
 	objCache    *cache.ObjectsCache
@@ -46,6 +56,7 @@ func DefaultCachesConfigs(logger *zap.Logger) *CachesConfig {
 
 func NewCache(cfg *CachesConfig) *Cache {
 	return &Cache{
+		testCache:   map[string]TestCacheValue{},
 		logger:      cfg.Logger,
 		listsCache:  cache.NewObjectsListCache(cfg.ObjectsList),
 		objCache:    cache.New(cfg.Objects),