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.

该 issue 未指出文件、测试或入口点。首先定位实例扩缩容和服务提供方案转换的路径，然后确定应如何授权和验证带标签的提供方案变更；当实例可以在带有不同标签的提供方案之间直接迁移，而无需使用无标签的 shim 时，即视为完成。

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