add KeyName -> std::Cow paths (#640)

Co-authored-by: Toby Lawrence <tobz@users.noreply.github.com>

Author: Javyre

metrics/src/key.rs

@@ -23,6 +23,11 @@ impl KeyName {
     pub fn as_str(&self) -> &str {
         &self.0
     }
+
+    /// Consumes this [`KeyName`], returning the inner [`SharedString`].
+    pub fn into_inner(self) -> SharedString {
+        self.0
+    }
 }
 
 impl<T> From<T> for KeyName
@@ -40,6 +45,12 @@ impl Borrow<str> for KeyName {
     }
 }
 
+impl From<KeyName> for std::borrow::Cow<'static, str> {
+    fn from(name: KeyName) -> Self {
+        name.0.into()
+    }
+}
+
 /// A metric identifier.
 ///
 /// A key represents both the name and labels of a metric.
@@ -131,6 +142,11 @@ impl Key {
         self.name.0.as_ref()
     }
 
+    /// Name of this key as a [`KeyName`]
+    pub fn name_shared(&self) -> KeyName {
+        self.name.clone()
+    }
+
     /// Labels of this key, if they exist.
     pub fn labels(&self) -> Iter<'_, Label> {
         self.labels.iter()