settings: accept trailing commas (#2606)

Z-2357

I've found a crate that handles both comments and trailing commas in
JSON. It is a fork of `serde_json`, but it is maintained & up-to-date.
Sadly RawValue seems to not play nicely with it; I've ran into
deserialisation issues around use of RawValue. For this PR I've migrated
to `Value` API.

Obviously this is just a point of discussion, not something I'd merge
straight away. There may be better solutions to this particular problem.

I've also noticed that `serde_json_lenient` does not handle trailing
commas after bindings array. I'm not sure how big of an issue that is.

Release Notes:
- Improved handling of trailing commas in settings files.
[#1322](https://github.com/zed-industries/community/issues/1322)

crates/gpui/src/app/action.rs

@@ -11,7 +11,7 @@ pub trait Action: 'static {
     fn qualified_name() -> &'static str
     where
         Self: Sized;
-    fn from_json_str(json: &str) -> anyhow::Result<Box<dyn Action>>
+    fn from_json_str(json: serde_json::Value) -> anyhow::Result<Box<dyn Action>>
     where
         Self: Sized;
 }
@@ -38,7 +38,7 @@ macro_rules! actions {
             $crate::__impl_action! {
                 $namespace,
                 $name,
-                fn from_json_str(_: &str) -> $crate::anyhow::Result<Box<dyn $crate::Action>> {
+                fn from_json_str(_: $crate::serde_json::Value) -> $crate::anyhow::Result<Box<dyn $crate::Action>> {
                     Ok(Box::new(Self))
                 }
             }
@@ -58,8 +58,8 @@ macro_rules! impl_actions {
             $crate::__impl_action! {
                 $namespace,
                 $name,
-                fn from_json_str(json: &str) -> $crate::anyhow::Result<Box<dyn $crate::Action>> {
-                    Ok(Box::new($crate::serde_json::from_str::<Self>(json)?))
+                fn from_json_str(json: $crate::serde_json::Value) -> $crate::anyhow::Result<Box<dyn $crate::Action>> {
+                    Ok(Box::new($crate::serde_json::from_value::<Self>(json)?))
                 }
             }
         )*

crates/gpui/src/app/window.rs

@@ -394,7 +394,7 @@ impl<'a> WindowContext<'a> {
             .iter()
             .filter_map(move |(name, (type_id, deserialize))| {
                 if let Some(action_depth) = handler_depths_by_action_type.get(type_id).copied() {
-                    let action = deserialize("{}").ok()?;
+                    let action = deserialize(serde_json::Value::Object(Default::default())).ok()?;
                     let bindings = self
                         .keystroke_matcher
                         .bindings_for_action_type(*type_id)