start implementing a skeleton of the v1 dump reader

dump/src/reader/v6.rs

@@ -0,0 +1,16 @@
+use std::{
+    fs::{self},
+    path::Path,
+};
+
+use time::OffsetDateTime;
+
+use crate::Result;
+
+type Metadata = crate::Metadata;
+
+pub fn date(dump: &Path) -> Result<OffsetDateTime> {
+    let metadata = fs::read(dump.join("metadata.json"))?;
+    let metadata: Metadata = serde_json::from_reader(metadata)?;
+    Ok(metadata.dump_date)
+}