Implement NWBEP001 (add EventsTable and more)

[rly]

Summary of changes

• Fix Implement NWBEP001 #625

Checklist

For all schema changes:

• Add release notes for the PR to docs/format/source/format_release_notes.rst.
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.
• Make sure that hdmf-common-schema points to the latest release and not the latest commit on the main branch.

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]

TODO: Update BehavioralEpochs docstring

[rly]

If I recall correctly, at our team discussion, we decided not to deprecate setting TimeSeries. continuity="instantaneous" because 1) it may still be the natural representation in some rare cases (e.g., a regularly sampled signal that happens to represent instantaneous values) and 2) warning/erroring on new in pynwb because it is deprecated breaks existing scripts that set this value, and that cost is not worth the value gained from deprecating continuity="instantaneous"at the schema level. Also unlikeBehavioralEventsandAnnotationSeries, which are dedicated containers designed for event data storage, TimeSeries` is a generic base type that has many different uses.

[oruebel]

Looks good to me. I added minor suggestion to clarify the docs. Feel free to accept/reject that suggestion as you deem appropriate.