Add a custom argparse help formatter that overrides the output
format to list items vertically.

The formatter is derived from argparse.HelpFormatter with minimal changes.

Co-authored-by: John Villalovos <john@sodarock.com>
Co-authored-by: Nejc Habjan <nejc.habjan@siemens.com>

In the CLI we need to make sure the components put into the path
portion of the URL are url-encoded. Otherwise they will be interpreted
as part of the path. For example can specify the project ID as a path,
but in the URL it must be url-encoded or it doesn't work.

Also stop adding the components of the path as query parameters in the
URL.

Closes: #783
Closes: #1498

Previously c8256a5933d745f70c7eea0a7d6230b51bac0fbc was done to fix
this but it missed two other failures.

BREAKING-CHANGE: The gitlab CLI will now accept CLI arguments
and environment variables for its global options in addition
to configuration file options. This may change behavior for
some workflows such as running inside GitLab CI and with
certain environment variables configured.

Fix functional test failure if config present and configured with
token.

Closes: #1791

BREAKING CHANGE: A config file is no longer needed to run
the CLI. python-gitlab will default to https://gitlab.com
with no authentication if there is no config file provided.
python-gitlab will now also only look for configuration
in the provided PYTHON_GITLAB_CFG path, instead of merging
it with user- and system-wide config files. If the
environment variable is defined and the file cannot be
opened, python-gitlab will now explicitly fail.