feat(header): add CAPSULE_PROTOCOL standard header (RFC 9297)

benches/src/header_map/basic.rs

@@ -537,6 +537,7 @@ const STD: &'static [HeaderName] = &[
     AUTHORIZATION,
     CACHE_CONTROL,
     CACHE_STATUS,
+    CAPSULE_PROTOCOL,
     CDN_CACHE_CONTROL,
     CONNECTION,
     CONTENT_DISPOSITION,

src/header/mod.rs

@@ -70,6 +70,7 @@ pub use self::name::{
     AUTHORIZATION,
     CACHE_CONTROL,
     CACHE_STATUS,
+    CAPSULE_PROTOCOL,
     CDN_CACHE_CONTROL,
     CONNECTION,
     CONTENT_DISPOSITION,

src/header/name.rs

@@ -350,6 +350,12 @@ standard_headers! {
     /// See [RFC 9211](https://www.rfc-editor.org/rfc/rfc9211.html).
     (CacheStatus, CACHE_STATUS, b"cache-status");
 
+    /// Indicates whether the Capsule Protocol is in use for a request or
+    /// response.
+    ///
+    /// See [RFC 9297](https://www.rfc-editor.org/rfc/rfc9297.html).
+    (CapsuleProtocol, CAPSULE_PROTOCOL, b"capsule-protocol");
+
     /// Specifies directives that allow origin servers to control the behavior of CDN caches
     /// interposed between them and clients separately from other caches that might handle the
     /// response.

tests/header_map.rs

@@ -388,6 +388,7 @@ const STD: &'static [HeaderName] = &[
     AUTHORIZATION,
     CACHE_CONTROL,
     CACHE_STATUS,
+    CAPSULE_PROTOCOL,
     CDN_CACHE_CONTROL,
     CONNECTION,
     CONTENT_DISPOSITION,

tests/header_map_fuzz.rs

@@ -273,6 +273,7 @@ fn gen_header_name(g: &mut StdRng) -> HeaderName {
         header::AUTHORIZATION,
         header::CACHE_CONTROL,
         header::CACHE_STATUS,
+        header::CAPSULE_PROTOCOL,
         header::CDN_CACHE_CONTROL,
         header::CONNECTION,
         header::CONTENT_DISPOSITION,