Merge branch 'submission-approval' into 'dev'

.gitlab-ci.yml

client/src/api/submissions.js

...t/src/components/ta_teacher_shared/SubmissionApproval.vue

client/src/components/ta_teacher_shared/Submissions.vue

client/src/router/teacher-routes.js

client/src/router/teaching-assistant-routes.js

server/src/migration/1603218352822-submissionApproval.ts

server/src/models/Submission.ts

server/src/routes/submissions.ts

server/src/util/parseSubmissionsForExport.ts

server/src/workers/exportSubmissions.ts

server/src/workers/pool.ts

server/src/workers/workerFunctions.ts

server/tests/e2e/integration.test.ts