feat(core): implement emoji model

closes #270

crates/core/models/src/v0/emojis.rs

@@ -0,0 +1,33 @@
+auto_derived!(
+    /// Emoji
+    pub struct Emoji {
+        /// Unique Id
+        #[cfg_attr(feature = "serde", serde(rename = "_id"))]
+        pub id: String,
+        /// What owns this emoji
+        pub parent: EmojiParent,
+        /// Uploader user id
+        pub creator_id: String,
+        /// Emoji name
+        pub name: String,
+        /// Whether the emoji is animated
+        #[cfg_attr(
+            feature = "serde",
+            serde(skip_serializing_if = "crate::if_false", default)
+        )]
+        pub animated: bool,
+        /// Whether the emoji is marked as nsfw
+        #[cfg_attr(
+            feature = "serde",
+            serde(skip_serializing_if = "crate::if_false", default)
+        )]
+        pub nsfw: bool,
+    }
+
+    /// Parent Id of the emoji
+    #[serde(tag = "type")]
+    pub enum EmojiParent {
+        Server { id: String },
+        Detached,
+    }
+);