Helper command to collect debugging info

[edvald]

It would be very useful to have a command that collects and archives information that would generally be useful for us when debugging user problems.

I suggest we make a garden get debug-info command (other suggestions for names welcome), that does the following:

1. Collect every garden.yml in the project, and store in a corresponding directory structure in a temporary folder. This should notably work even if the project doesn’t successfully validate.
2. For every found garden.yml, see if there is an error.log file next to it, if so copy it next to the garden.yml in the temporary directory.
3. For each provider that specifies it, call the getDebugInfo handler (which we need to add) The handler output schema should have an info key, which allows any object, which is then stored in the temp dir under <provider-name>/info.json. Later we may wish to add more specific keys, or a way to output individual files, but that can wait.
4. Collect some basic system info, as well as the Garden version into a JSON or YAML file and store at the top of the temp directory.
5. Zip the temp directory into a garden-debug-<timestamp>.zip file and delete the temp directory.

For step 3, we should at a minimum make a handler for the Kubernetes plugin, that does the following:

1. Calls kubectl get all —all-namespaces —output yaml and stores it under clusterResources.
2. Calls kubectl version --output yaml and stores it under version
3. Possibly other useful info to add?

We should then make sure to update our bug report issue template, once the command is released.

[edvald]

Done in #778