cram/io/reader/header: Discard rest of header container

This consumes the trailer of the first block, subsequent expansion
blocks, and container padding.

noodles-cram/src/async/io/reader/header.rs

@@ -88,9 +88,14 @@ where
 {
     let mut container_reader = reader.container_reader().await?;
 
-    let mut raw_sam_header_reader = container_reader.raw_sam_header_reader().await?;
-    let header = read_sam_header(&mut raw_sam_header_reader).await?;
-    raw_sam_header_reader.discard_to_end().await?;
+    let header = {
+        let mut raw_sam_header_reader = container_reader.raw_sam_header_reader().await?;
+        let header = read_sam_header(&mut raw_sam_header_reader).await?;
+        raw_sam_header_reader.discard_to_end().await?;
+        header
+    };
+
+    container_reader.discard_to_end().await?;
 
     Ok(header)
 }

noodles-cram/src/async/io/reader/header/container.rs

@@ -32,4 +32,8 @@ where
 
         Ok(sam_header::Reader::new(reader, len))
     }
+
+    pub(super) async fn discard_to_end(&mut self) -> io::Result<u64> {
+        io::copy(&mut self.inner, &mut io::sink()).await
+    }
 }

noodles-cram/src/io/reader/header.rs

@@ -86,9 +86,14 @@ where
 {
     let mut container_reader = reader.container_reader()?;
 
-    let mut raw_sam_header_reader = container_reader.raw_sam_header_reader()?;
-    let header = read_sam_header(&mut raw_sam_header_reader)?;
-    raw_sam_header_reader.discard_to_end()?;
+    let header = {
+        let mut raw_sam_header_reader = container_reader.raw_sam_header_reader()?;
+        let header = read_sam_header(&mut raw_sam_header_reader)?;
+        raw_sam_header_reader.discard_to_end()?;
+        header
+    };
+
+    container_reader.discard_to_end()?;
 
     Ok(header)
 }

noodles-cram/src/io/reader/header/container.rs

@@ -34,4 +34,8 @@ where
 
         Ok(sam_header::Reader::new(reader, len))
     }
+
+    pub(super) fn discard_to_end(&mut self) -> io::Result<u64> {
+        io::copy(&mut self.inner, &mut io::sink())
+    }
 }