make ConfigMap collector namespace-optional

[adamancini]

Description, Motivation and Context

When no namespace is given in the ConfigMaps collector spec, use the namespace from the current kubectl context.

Fixes: #907

Checklist

• New and existing tests pass locally with introduced changes.
• Tests for the changes have been added (for bug fixes / features)
• The commit message(s) are informative and highlight any breaking changes
• Any documentation required has been added/updated. For changes to https://troubleshoot.sh/ create a PR here

Does this PR introduce a breaking change?

• Yes
• No

[adamancini]

Using the test spec from my PR:

tail support-bundle-2023-06-06T10_09_37/configmaps/* support-bundle-2023-06-06T10_09_37/configmaps-errors/* 
==> support-bundle-2023-06-06T10_09_37/configmaps/cluster-info.json <==
{
  "namespace": "",
  "name": "cluster-info",
  "key": "",
  "configMapExists": false,
  "keyExists": false,
  "data": null
}
==> support-bundle-2023-06-06T10_09_37/configmaps/does-not-exist.json <==
{
  "namespace": "",
  "name": "does-not-exist",
  "key": "",
  "configMapExists": false,
  "keyExists": false,
  "data": null
}
==> support-bundle-2023-06-06T10_09_37/configmaps/kube-proxy.json <==
{
  "namespace": "",
  "name": "kube-proxy",
  "key": "",
  "configMapExists": true,
  "keyExists": false,
  "data": null
}
==> support-bundle-2023-06-06T10_09_37/configmaps/kube-root-ca.crt.json <==
{
  "namespace": "",
  "name": "kube-root-ca.crt",
  "key": "",
  "configMapExists": true,
  "keyExists": false,
  "data": null
}
==> support-bundle-2023-06-06T10_09_37/configmaps/kube-system <==

==> support-bundle-2023-06-06T10_09_37/configmaps-errors/cluster-info.json <==
[
  "configmaps \"cluster-info\" not found"
]
==> support-bundle-2023-06-06T10_09_37/configmaps-errors/does-not-exist.json <==
[
  "configmaps \"does-not-exist\" not found"
]%                                                                                                   

[diamonwiggins]

Approved with a suggestion, and a caveat of there has been some discussion recently if we should ever use the kubeconfig context's namespace at all. Not sure what the argument is there, but i don't object to this change.

[diamonwiggins]

Approved with a suggestion, and a caveat of there has been some discussion recently if we should ever use the kubeconfig context's namespace at all. Not sure what the argument is there, but i don't object to this change.