feat: Add support for externally tagged enums

Also did a massive code refactor that helped simplify the
implementation.

tests/notification.rs

@@ -1,5 +1,25 @@
+use std::collections::HashMap;
+
 use lua_typed::Typed;
 
+#[derive(Typed)]
+#[serde(rename_all = "snake_case", tag = "action")]
+pub enum ActionType {
+    Broadcast { extras: HashMap<String, String> },
+    // View,
+    // Http
+}
+
+#[test]
+fn action_type() {
+    insta::assert_snapshot!(<ActionType as Typed>::generate_full().unwrap(), @r#"
+    ---@class ActionType
+    ---@field action
+    ---| "broadcast"
+    ---@field extras table<string, string>?
+    "#);
+}
+
 #[derive(Typed)]
 #[repr(u8)]
 #[serde(rename_all = "snake_case")]
@@ -25,22 +45,23 @@ fn priority() {
 
 #[derive(Typed)]
 pub struct Action {
-    // #[serde(flatten)]
-    // pub action: ActionType,
+    #[serde(flatten)]
+    pub action: ActionType,
     pub label: String,
     pub clear: Option<bool>,
 }
 
-// #[test]
-// fn action() {
-//     insta::assert_snapshot!(<Action as Typed>::generate_full().unwrap(), @r#"
-//     ---@class Action
-//     ---@field action "broadcast"
-//     ---@field extras table<string, string>?
-//     ---@field label string?
-//     ---@clear clear bool?
-//     "#);
-// }
+#[test]
+fn action() {
+    insta::assert_snapshot!(<Action as Typed>::generate_full().unwrap(), @r#"
+    ---@class Action
+    ---@field action
+    ---| "broadcast"
+    ---@field extras table<string, string>?
+    ---@field label string
+    ---@field clear boolean?
+    "#);
+}
 
 #[derive(Typed)]
 pub struct Notification {

tests/ui/complex_struct.stderr

@@ -1,16 +1,16 @@
-error: Only basic enums are supported by Typed
+error: Typed supports enum variants with fields only when the enum is externally tagged
  --> tests/ui/complex_struct.rs:6:6
   |
 6 |     B(String),
   |      ^^^^^^^^
 
-error: Only basic enums are supported by Typed
+error: Typed supports enum variants with fields only when the enum is externally tagged
  --> tests/ui/complex_struct.rs:7:6
   |
 7 |     C(u8),
   |      ^^^^
 
-error: Only basic enums are supported by Typed
+error: Typed supports enum variants with fields only when the enum is externally tagged
  --> tests/ui/complex_struct.rs:8:7
   |
 8 |     D { test: f32 },

tests/ui/tuple_enum_untagged.rs

@@ -0,0 +1,9 @@
+use lua_typed::Typed;
+
+#[derive(Typed)]
+enum Test {
+    A,
+    D { test: f32 },
+}
+
+fn main() {}

tests/ui/tuple_enum_untagged.stderr

@@ -0,0 +1,5 @@
+error: Typed supports enum variants with fields only when the enum is externally tagged
+ --> tests/ui/tuple_enum_untagged.rs:6:7
+  |
+6 |     D { test: f32 },
+  |       ^^^^^^^^^^^^^