Clarify support for Simid Wrapper

[Knotschi]

The vast specification is not very clear if it should be possible to have a SIMID creative inside a vast Wrapper, while the actual MediaFile (e.g. an mp4 video) should be served from the wrapped vast tag.

Right now googles ImaSdk for example is not supporting it. They also seem to not be sure if that should be supported according to the vast spec or not.

here is an example of a vast wrapper which I would expect to show the simid ad and the mp4:
https://assets.redpineapplemedia.com/vast/simid-wrapper/simid-wrapper.xml
Currently, when showing this wrapper in googles imasdk the simid is not shown:
https://googleads.github.io/googleads-ima-html5/vsi/?tag=https%253A%252F%252Fassets.redpineapplemedia.com%252Fvast%252Fsimid-wrapper%252Fsimid-wrapper.xml

Here is an other example where the SIMID and the video mp4 are in the same vast tag (no wrapper), just to show the expected result:
https://googleads.github.io/googleads-ima-html5/vsi/?tag=https%253A%252F%252Fassets.redpineapplemedia.com%252Fvast%252Fsimid-wrapper%252Fsimid-vast.xml

Could you clarify if this should be supported by the spec? If currently not: could you consider adding support for this case in the next vast version?