💾 Setup SQLite database (#3)

* Add SQLite setup

* Add basic user entity and repository

* Adjust DB naming

* Consolidate properties

src/test/java/de/mlessmann/certassist/repositories/UserRepositoryTest.java

@@ -0,0 +1,24 @@
+package de.mlessmann.certassist.repositories;
+
+import de.mlessmann.certassist.models.User;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@SpringBootTest
+class UserRepositoryTest {
+
+    @Autowired
+    private UserRepository userRepository;
+
+    @Test
+    void findUserById() {
+        final User user = new User();
+        user.setUsername("test");
+        userRepository.save(user);
+
+        assertThat(userRepository.findUserById(user.getId()).getUsername()).isEqualTo("test");
+    }
+}