Extension blocks that might reuse existing extension simulator parts

Describe the bug

Arising from two extensions that depend on existing neopixel and servo extensions.
https://github.com/microsoft/pxt-microbit/pull/6123#issuecomment-2731100052
https://github.com/microsoft/pxt-microbit/pull/6121#issuecomment-2730195155

I created some examples with code in custom.ts.

Wrapping existing calls that would show simulator parts, in functions with parameters, causes the simulator to jump down, but no simulated part is shown.
https://makecode.microbit.org/_Ku2KqDDxcPD6

I discovered that it's easy to stop the simulator moving, and parts appearing, by adding, for example,
//% hiddenParts=microservo or //% hiddenParts="neopixel" to any block
https://makecode.microbit.org/_82tEEvb1sdtT

A block with no parameters triggers the servo to appear, but blocks with parameters still seem to have no effect on the simulation.
https://makecode.microbit.org/_2vXK82gF5U8s

Start by reproducing the simulator behavior using the custom.ts examples and the linked MakeCode projects. Compare wrappers around existing neopixel and servo calls, including the examples using hiddenParts, and identify why parameterized blocks do not show simulated parts. Done means the simulator remains positioned correctly and displays the expected servo or neopixel part for these extension blocks.