routing: add block cache to CfFilteredChainView

This commit adds the block cache to the CfFilteredChainView struct
and wraps its GetBlock function so that block cache mutex map is used
when the call to neutrino's GetBlock function is called.

routing/chainview/interface_test.go

@@ -895,7 +895,11 @@ var interfaceImpls = []struct {
 				os.RemoveAll(spvDir)
 			}
 
-			chainView, err := NewCfFilteredChainView(spvNode)
+			blockCache := blockcache.NewBlockCache(10000)
+
+			chainView, err := NewCfFilteredChainView(
+				spvNode, blockCache,
+			)
 			if err != nil {
 				return nil, nil, err
 			}