Create client to establish connection with discord and add basic framework with sample command

cipher_database/src/postgres/repository/mod.rs

@@ -0,0 +1,49 @@
+use diesel_async::pooled_connection::bb8::Pool;
+use diesel_async::pooled_connection::bb8::PooledConnection;
+use diesel_async::AsyncPgConnection;
+use cipher_core::repository::Repository;
+use cipher_core::repository::RepositoryError;
+use cipher_core::repository::RepositoryProvider;
+
+use crate::BackendError;
+
+mod user_repository;
+
+pub struct PostgresRepository<'a> {
+    conn: PooledConnection<'a, AsyncPgConnection>,
+}
+
+impl<'a> PostgresRepository<'a> {
+    pub fn new(conn: PooledConnection<'a, AsyncPgConnection>) -> Self {
+        Self { conn }
+    }
+}
+
+impl Repository for PostgresRepository<'_> {
+    type BackendError = BackendError;
+}
+
+pub struct PostgresRepositoryProvider {
+    pool: Pool<AsyncPgConnection>,
+}
+
+impl PostgresRepositoryProvider {
+    pub fn new(pool: Pool<AsyncPgConnection>) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait::async_trait]
+impl RepositoryProvider for PostgresRepositoryProvider {
+    type BackendError = BackendError;
+
+    type Repository<'a> = PostgresRepository<'a>;
+
+    async fn get(&self) -> Result<Self::Repository<'_>, RepositoryError<Self::BackendError>> {
+        self.pool
+            .get()
+            .await
+            .map(PostgresRepository::new)
+            .map_err(|err| RepositoryError(BackendError::from(err)))
+    }
+}