propose more stimulus types

[CodyCBakerPhD]

Summary of changes

@oruebel @rly

From discussion last week, is this the way were allow more generic types to the stimulus area of the file?

Checklist

For all schema changes:

• Add release notes for the PR to docs/format/source/format_release_notes.rst.

If this is the first schema change after a schema release (i.e., the version string in core/nwb.namespace.yaml does not
end in "-alpha"), then:

• Update the version string in core/nwb.namespace.yaml and core/nwb.file.yaml to the next major/minor/patch
  version with the suffix "-alpha". For example, if the current version is 2.4.0 and this is a minor change, then the
  new version string should be "2.5.0-alpha".
• Update the value of the version variable in docs/format/source/conf.py to the next version without the
  suffix "-alpha", e.g., "2.5.0".
• Update the value of the release variable in docs/format/source/conf.py to the next version with the suffix
  "-alpha", e.g., "2.5.0-alpha".
• Add a new section in the release notes docs/format/source/format_release_notes.rst for the new version
  with the date "Upcoming" in parentheses.

[rly]

Yes. If this is ready, I can write the corresponding pynwb PR, or you can if you want. Let me know!

[CodyCBakerPhD]

Yes. If this is ready, I can write the corresponding pynwb PR, or you can if you want.

If you can take over this it will likely go much faster; I can certainly help write tests and give real life use cases

There's several applications we'd love to be able to utilize this in for current conversions; one for the Allen Institute, there are some visual stimuli presented described using simple DynamicTable types; then for holographic stimulation we may be looking into non-TimeSeries based representations more similar to LabeledEvents; I guess there's also other ndx-events based representations that are also considered 'stimuli' rather than just naturally observed events