Add example of an automated proposal signing program

[wizzeh]

This PR (sorry) does a couple of things:

1. It breaks out the existing workspace into 3 separate crates. The existing example programs rely on old versions of dependencies that can't be upgraded yet. Something (probably the bpf dependency resolver?) is requiring that the workspace crate only have a single version of each dependency. This is preventing new work from being merged.
2. It adds a new program, signatory-no-transfers, an example Anchor program which could be added as a required signer to a governance. The program will only sign off on proposals that don't involve token transfers. This should provide a framework for anyone who wants to create automatic constitutional rules for a governance.

Since this PR relies on this work that I did at @SebastianBor's suggestion, I'm marking it as a draft until that work is merged.

[wizzeh]

My work on spl-gov has been merged so I'm moving this out of draft.