Sample projects should be brought up to date, included in docs, built/tested with each PR or release

[hlship]

We have a scattering of older samples to demonstrate different features, but they are suffering from bit-rot.

By updating them to track the latest version of Pedestal, and building them (with each PR? On each merge to master?) with at least cursory tests to show that they still operate, we can provide a much more useful resource.

Potentially, the samples could be packaged as downloadable zip files as part of the documentation build.