✨ [no_ci] Add friend interface

Sources/src/main/kotlin/allin/data/FriendDataSource.kt

@@ -0,0 +1,9 @@
+package allin.data
+
+interface FriendDataSource {
+    fun addFriend(sender: String, receiver: String)
+    fun getFriendFromUserId(id: String)
+    fun getFriendFromUsername(username: String)
+    fun deleteFriend(senderId: String, receiverId: String)
+    fun isFriend(firstUser: String, secondUser: String)
+}

Sources/src/main/kotlin/allin/data/postgres/PostgresFriendDataSource.kt

@@ -0,0 +1,27 @@
+package allin.data.postgres
+
+import allin.data.FriendDataSource
+import org.ktorm.database.Database
+
+class PostgresFriendDataSource(private val database: Database) : FriendDataSource {
+    override fun addFriend(sender: String, receiver: String) {
+//        TODO("Not yet implemented")
+    }
+
+    override fun getFriendFromUserId(id: String) {
+        TODO("Not yet implemented")
+    }
+
+    override fun getFriendFromUsername(username: String) {
+        TODO("Not yet implemented")
+    }
+
+    override fun deleteFriend(senderId: String, receiverId: String) {
+        TODO("Not yet implemented")
+    }
+
+    override fun isFriend(firstUser: String, secondUser: String) {
+        TODO("Not yet implemented")
+    }
+
+}