* Fixes issue where proxy support only honored server address via K3S_URL, not CLI or config.
* Fixes crash when agent proxy is enabled, but proxy env vars do not return a proxy URL for the server address (server URL is in NO_PROXY list).
* Adds tests
Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
Co-authored-by: Brad Davidson <brad.davidson@rancher.com>