added initial test setup with docker compose, jdk17/junit5 testrunner and calculator exercise

docker-compose.yaml

+version: '2'
+services:
+services:
+  mariadb-dtt:
+    container_name: moodledb-dtt
+    image: docker.io/bitnami/mariadb:11.1
+    environment:
+      # ALLOW_EMPTY_PASSWORD is recommended only for development.
+      - ALLOW_EMPTY_PASSWORD=yes
+      - MARIADB_USER=bn_moodle
+      - MARIADB_DATABASE=bitnami_moodle
+      - MARIADB_CHARACTER_SET=utf8mb4
+      - MARIADB_COLLATE=utf8mb4_unicode_ci
+    volumes:
+      - 'mariadb_data_dtt:/bitnami/mariadb'
+  moodle-dtt:
+    container_name: moodle-dtt
+    image: docker.io/bitnami/moodle:4.3
+    ports:
+      - '81:8080'
+      - '444:8443'
+    environment:
+      - MOODLE_DATABASE_HOST=mariadb-dtt
+      - MOODLE_DATABASE_PORT_NUMBER=3306
+      - MOODLE_DATABASE_USER=bn_moodle
+      - MOODLE_DATABASE_NAME=bitnami_moodle
+      # ALLOW_EMPTY_PASSWORD is recommended only for development.
+      - ALLOW_EMPTY_PASSWORD=yes
+    volumes:
+      - 'moodle_data_dtt:/bitnami/moodle'
+      - 'moodledata_data_dtt:/bitnami/moodledata'
+    depends_on:
+      - mariadb-dtt
+  backend:
+    container_name: backendcomposedtt
+    image: hftstuttgart/dta-backend:latest
+    user: "${UID}:${GID}"
+    volumes: 
+      - /var/run/docker.sock:/var/run/docker.sock
+      - '/tmp/dtt-tests:/tmp/dtt-tests'
+volumes:
+  mariadb_data_dtt:
+    driver: local
+  moodle_data_dtt:
+    driver: local
+  moodledata_data_dtt:
+    driver: local

student.txt

+dtt::https://transfer.hft-stuttgart.de/gitlab/dtt/example_openjdk11-junit5-calculator-submission.git::none::none
\ No newline at end of file

teacher-dta.txt

+dtt::https://transfer.hft-stuttgart.de/gitlab/dtt/example_openjdk11-junit5-calculator-test.git::none::none::hftstuttgart/dta-jdk17-junit5-testrunner:latest