CLI returns exit code 1 when help or --version args passed

[eysi09]

The following commands return exit code 1 instead of 0:

garden --version
garden help

Note that garden --help returns 0 as expected and garden version returns 0 if in a project directory but fails with Not a project directory (or any of the parent directories): ... otherwise.

[eysi09]

We need to fix this for Garden to work properly in CI.

[edvald]

Hmm, why is that?

[eysi09]

Well, this was kind of poorly phrased, Garden works fine in CI regardless.

The above was more of a note to self since I'm trying Garden on different CI systems and like to verify that it's properly installed on the agent by running garden --version. However, that causes the CI job to fail because it returns exit code 1.

[eysi09]

Closed in #669