bug: deploy indicates success when nothing was deployed

[techfg]

When executing deploy, several situations can occur with the command indicating success in the logs but resulting in nothing being deployed.

The situations are:

1. The targetDirectory exists but is empty
2. The targetDirectory exists, is not empty, but contains no valid metadata files
3. The server returned valid JSON from GetDeployPlan but did not return a skuidMetadataService plan or a skuidCloudDataService plan

Regardless of which of the situations above occur, the user should be informed in an appropriate way (warning indicating nothing deployed and/or outright error) as currently, they could think their entire site deployed but nothing deployed.

Bonus item: When GetDeployPlan returns valid JSON and it contains a plan for skuidMetadataService and/or skuidCloudDataService but the plan doesn't contain complete information (e.g., missing the Host or Endpoint), the error emitted to the logs is HTTP 404 Not Found which is rather meaningless to a user so this error could be improved.