Move all entities to their own folder.

src/database/entities/message.rs

@@ -0,0 +1,22 @@
+use mongodb::bson::DateTime;
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct PreviousEntry {
+    pub content: String,
+    pub time: DateTime,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Message {
+    #[serde(rename = "_id")]
+    pub id: String,
+    pub nonce: Option<String>,
+    pub channel: String,
+    pub author: String,
+
+    pub content: String,
+    pub edited: Option<DateTime>,
+
+    pub previous_content: Vec<PreviousEntry>,
+}