Removing 'task' functionality, replacing it with extended process status.

docs/api.md

examples/external_project_parallel_upload/upload.py

examples/external_project_upload/upload.py

examples/uploading/bulk_upload.py

nomad/app/flask/api/mirror.py

nomad/app/flask/api/upload.py

nomad/app/v1/routers/uploads.py

nomad/cli/admin/admin.py

nomad/cli/admin/migrate.py

nomad/cli/admin/uploads.py

nomad/cli/client/integrationtests.py

nomad/cli/client/upload.py

nomad/processing/__init__.py

nomad/processing/base.py

nomad/processing/data.py

tests/app/flask/test_api.py

tests/app/flask/test_bravado.py

tests/app/v1/conftest.py

tests/app/v1/routers/test_uploads.py

tests/processing/test_base.py