WIP: Napari playback of spyglass entries

[samuelbray32]

Description

In conjuction with nwb viewer package development here

Features / To do

• One line generation of video and ephys playback for an epoch
• Mixin method make_viewer that calls fetch_nwb to get spyglass-organized nwb_objects and builds an appropriate viewer based on class type
• update requirements (pending pip release of nwb_data_viewer)

Checklist:

• This PR should be accompanied by a release: (yes/no/unsure)
• If release, I have updated the CITATION.cff
• This PR makes edits to table definitions: (yes/no)
• If table edits, I have included an alter snippet for release notes.
• If this PR makes changes to position, I ran the relevant tests locally.
• I have updated the CHANGELOG.md with PR number and description.
• I have added/edited docs/notebooks to reflect the changes

[edeno]

Let's make sure to make napari and the viewer optional.