Add a cache for gallery thumbnails (#496)

graphql/documents/data/config.graphql

@@ -2,6 +2,7 @@ fragment ConfigGeneralData on ConfigGeneralResult {
   stashes
   databasePath
   generatedPath
+  cachePath
   maxTranscodeSize
   maxStreamingTranscodeSize
   forceMkv

graphql/schema/types/config.graphql

@@ -14,6 +14,8 @@ input ConfigGeneralInput {
   databasePath: String
   """Path to generated files"""
   generatedPath: String
+  """Path to cache"""
+  cachePath: String
   """Max generated transcode size"""
   maxTranscodeSize: StreamingResolutionEnum
   """Max streaming transcode size"""
@@ -49,7 +51,9 @@ type ConfigGeneralResult {
   databasePath: String!
   """Path to generated files"""
   generatedPath: String!
-    """Max generated transcode size"""
+  """Path to cache"""
+  cachePath: String!
+  """Max generated transcode size"""
   maxTranscodeSize: StreamingResolutionEnum
   """Max streaming transcode size"""
   maxStreamingTranscodeSize: StreamingResolutionEnum

graphql/schema/types/metadata.graphql

@@ -3,6 +3,8 @@ input GenerateMetadataInput {
   previews: Boolean!
   markers: Boolean!
   transcodes: Boolean!
+  """gallery thumbnails for cache usage"""
+  thumbnails: Boolean!
 }
 
 input ScanMetadataInput {
@@ -22,4 +24,4 @@ type MetadataUpdateStatus {
   progress: Float!
 	status: String!
   message: String!
-}
+}