Define a mechanism to log data as explicitly invalid

[jleibs]

Compared to "Clearing" data, which has semantics of "this data, which was valid, has now expired" sometimes it is useful to instead log that a component itself represents invalid data.

For example, when an algorithm doesn't converge or outputs a bad value. We know a concrete timestamp when the invalid data was computed, and it's helpful to be able to represent this in the timeline explicitly.

We already have two ways of representing non-data:

• [ ] -- the data batch itself is empty
• [ Null ] the data itself is unset

We need to think through if one of these can be unambiguously used in the case of "invalid" vs "unset" data, or if we would need to introduce an alternative parallel mechanism.

[Wumpf]

Very related. if not redundant to

• Allow archetypes to clear and/or update existing components #3381