Refactor how service override booting is handled when stacked #117
Description
Bootable service overrides are booted directly, but because the stacked override implements the interface it is booted, with it proxying to its child overrides. This should be refactored so that each override, within a stacked override, is booted individually.
The primary reason for this, is that the ServiceOverrideBooted event is currently not of much use when using a stacked override.