See https://docs.gitlab.com/ee/api/group_access_tokens.html

chore: add `pprint()` and `pformat()` methods to RESTObject

This is useful in debugging and testing. As can easily print out the
values from an instance in a more human-readable form.

test: add logging to `tests/functional/conftest.py`

I have found trying to debug issues in the functional tests can be
difficult. Especially when trying to figure out failures in the CI
running on Github.

Add logging to `tests/functional/conftest.py` to have a better
understanding of what is happening during a test run which is useful
when trying to troubleshoot issues in the CI.

We were using `str.replace()` calls to take care of URL encoding
issues.

Switch them to use our `utils._url_encode()` function which itself uses
`urllib.parse.quote()`

Closes: #1356

The arguments `should_remove_source_branch` and
`merge_when_pipeline_succeeds` are optional arguments. We should not
be setting any default value for them.

https://docs.gitlab.com/ee/api/merge_requests.html#accept-mr

Closes: #1750

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.