Add --group support to uv add and uv remove (#8108)

Part of #8090

Adds the ability to add and remove dependencies from arbitrary groups
using `uv add` and `uv remove`. Does not include resolving with the new
dependencies — tackling that in #8110.

Additionally, this does not yet resolve interactions with the existing
`dev` group — we'll tackle that separately as well. I probably won't
merge the stack until that design is resolved.

crates/uv-normalize/src/group_name.rs

@@ -3,7 +3,7 @@ use std::fmt::{Display, Formatter};
 use std::str::FromStr;
 use std::sync::LazyLock;
 
-use serde::{Deserialize, Deserializer};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 use crate::{validate_and_normalize_owned, validate_and_normalize_ref, InvalidNameError};
 
@@ -41,6 +41,15 @@ impl<'de> Deserialize<'de> for GroupName {
     }
 }
 
+impl Serialize for GroupName {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        self.0.serialize(serializer)
+    }
+}
+
 impl Display for GroupName {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         self.0.fmt(f)