Remove parsers submodule

.gitmodules

MANIFEST.in

default_plugins.txt

dependencies/parsers/atomistic

dependencies/parsers/database

dependencies/parsers/electronic

dependencies/parsers/simulation

dependencies/parsers/workflow

gui/tests/artifacts.js

gui/tests/env.js

gui/tests/nomad.yaml

nomad/config/defaults.yaml

nomad/config/models/plugins.py

nomad/datamodel/metainfo/simulation/__init__.py

nomad/parsing/parser.py

nomad/parsing/parsers.py

pyproject.toml

requirements-dev.txt

requirements-plugins.txt

requirements.txt