Make the inclusion bdSeq metric on ncmd/dcmd optional

[joosttissen]

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Ignition cannot handle the bdSeq on ncmd/dcmd messages, it's giving the following exceptions:

Reading the sparkplugB specs I can only find that the bdSeq metric MUST be included on BIRTH/NDEATH not on any other message type. I can see that there used to be an setting to exclude the bdSeq metric from other messages based on #13.

If you agree I would like to add this setting back in the current codebase. Let me know and I'll create a PR.

[SeppPenner]

I guess this is a bug with version 3 of Sparkplug now as the metric isn't allowed anymore, but I need to check the specs again.