add tools::json for canonical json generation

moving this from backup::manifest, no functional changes

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/tools.rs

@@ -28,6 +28,7 @@ pub mod format;
 pub mod fs;
 pub mod fuse_loop;
 pub mod http;
+pub mod json;
 pub mod logrotate;
 pub mod loopdev;
 pub mod lru_cache;