Add option to scale instance to different tagged service offering

### The required feature described as a wish

As an end-user, I would like to be able to scale an existing instance to a service offering with a different hosttag than the current service offering assigned to the instance. If not unversially allowed by default, an option to allow for this to be enabled would be very helpful.

As it stands today, making this transition requires using an untagged offering as a "shim" to then transition to another offering. This is a bit of a clunky user experience that could easily create confusion for end user.

The issue does not identify files, tests, or entry points. Start by locating the instance scaling and service-offering transition paths, then determine how a tagged offering change should be authorized and validated; done means an instance can move directly between differently tagged offerings without using an untagged shim.

Written by the indexing model from the issue text.