[#390] frostfs-cli: Pass bearer token to Tree srv

* Add --bearer flag for "tree" subcommand

Signed-off-by: Airat Arifullin a.arifullin@yadro.com

cmd/frostfs-cli/modules/tree/get_by_path.go

@@ -71,7 +71,7 @@ func getByPath(cmd *cobra.Command, _ []string) {
 		Path:          strings.Split(path, "/"),
 		LatestOnly:    latestOnly,
 		AllAttributes: true,
-		BearerToken:   nil, // TODO: #1891 add token handling
+		BearerToken:   common.ReadBearerToken(cmd, bearerFlagKey).Marshal(),
 	}
 
 	commonCmd.ExitOnErr(cmd, "message signing: %w", tree.SignMessage(req, pk))