[tools] Normalize command line description.

Other tools start with lowercase.
[tools] httpSignature param setup option.

- Pass in pseudo param _httpSignatureFromConfig to setup key and keyId.
- This feature is used in multiple places.
[tools] Improve keys tool help.
[lib] Rename documentLoader function.

- Be more consistent and use jsonLdDocumentLoader.
[tools] Skip output of falsey data.

Skipping falsey output makes it easier for the usage pattern of trying
to output request results which could have been empty and returned null.
[tools] Add buget tool.

This tool lets you manage your budgets:
- list all budgets
- show a single budget
- create a new budget
- delete a budget
- update various budget properties
- add/delete vendors associated with a budget