Implement nonfunctional COPY and MOVE method

Fixes #69 for now

crates/dav/src/header/overwrite.rs

@@ -1,9 +1,19 @@
+use axum::{body::Body, extract::FromRequestParts, response::IntoResponse};
 use thiserror::Error;
 
 #[derive(Error, Debug)]
 #[error("Invalid Overwrite header")]
 pub struct InvalidOverwriteHeader;
 
+impl IntoResponse for InvalidOverwriteHeader {
+    fn into_response(self) -> axum::response::Response {
+        axum::response::Response::builder()
+            .status(axum::http::StatusCode::BAD_REQUEST)
+            .body(Body::new("Invalid Overwrite header".to_string()))
+            .expect("this always works")
+    }
+}
+
 #[derive(Debug, PartialEq, Default)]
 pub enum Overwrite {
     #[default]
@@ -17,6 +27,21 @@ impl Overwrite {
     }
 }
 
+impl<S: Send + Sync> FromRequestParts<S> for Overwrite {
+    type Rejection = InvalidOverwriteHeader;
+
+    async fn from_request_parts(
+        parts: &mut axum::http::request::Parts,
+        _state: &S,
+    ) -> Result<Self, Self::Rejection> {
+        if let Some(overwrite_header) = parts.headers.get("Overwrite") {
+            overwrite_header.as_bytes().try_into()
+        } else {
+            Ok(Self::default())
+        }
+    }
+}
+
 impl TryFrom<&[u8]> for Overwrite {
     type Error = InvalidOverwriteHeader;