[skip ci] Implement REST API handler to return the version

[zjs]

Resolves #6016.

Note: this change builds on #6132 and, once approved, I would like this to land as the third commit on feature/vic-machine-service.

[caglar10ur]

how about returning the version directly here without version_get.go (assuming it works)?

api.GetVersionHandler = operations.GetVersionHandlerFunc(func(params operations.GetVersionParams) middleware.Responder {
        return operations.NewGetVersionOK().WithPayload(version.GetBuild().ShortVersion()) 
 })

[zjs]

I believe that would work fine (and is similar to how I implemented it initially), but I think there's a lot of value in having the APIs handled consistently.

If configure_vic_machine.go is simply a dispatcher to logic in other files, and never the place where handler logic is implemented, I think it's easier to reason about. (It also allows for consistent patterns around, for example, testing.)

[jzt]

Might be worth rebasing - I seem to remember these changes in a different PR (@hickeng's) that I suspect has already been merged.

[zjs]

It looks like this picked up a bunch of random CLs from other people. Doing a force push seems to have cleared that up.