Bump development tools: mypy, codespell, isort, ...

Move all tools configuration in pyproject.toml.

Remove no longer needed mypy overrides.

Since the release of pytest 8.1, some pytest options are no longer
needed and editable install can be used when running tests using tox.

Related to swh/meta#5075.

Related to swh/meta#4960

Related to swh/meta#4959

accepts Keycloak server details and an aiocache cache instance
returns a starlette SimpleUser along with permissions

- pre-commit from 4.1.0 to 4.3.0,
- codespell from 2.2.1 to 2.2.2,
- black from 22.3.0 to 22.10.0 and
- flake8 from 4.0.1 to 5.0.4. Also freeze flake8 dependencies.

Also change flake8's repo config to github (the gitlab mirror
being outdated).

black is considered stable since release 22.1.0 and the version
we are currently using is quite outdated and not compatible with
click 8.1.0, so it is time to bump it to its latest stable release.

Please note that E501 pycodestyle warning related to line length
is replaced by B950 one from flake8-bugbear as recommended by black.
https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#line-length

Related to T3922

This also drops spurious copyright headers to those files if present.

Related to T3812

Enable to check package documentation can be built without producing
sphinx warnings.

The sphinx environment is designed to be used in continuous integration
in order to prevent breaking documentation build when committing changes.

The sphinx-dev environment is designed to be used inside a full swh
development environment.

Related to T3258

That class is a custom User proxy model for remote users storing OpenID Connect related
data (profile containing authentication tokens, ...).

The model is also not saved to database as all users are already stored in the Keycloak
one.

That class will be used for example by both the webapp and the deposit.

Related to T3079

Related to T3079