fix new viewer after image rotation

[kecnry]

Description

This pull request generalizes the logic for adding a new viewer so other configs/viewers that don't use the concept of reference data and wcs-linking (introduced in #2179) do not raise a traceback.

This is a minor change to a feature not-yet-released, so does not need a changelog entry of its own (although we could append the PR number to the image rotation PR if a link between the PRs in GitHub is not sufficient papertrail).

Change log entry

• Is a change log needed? If yes, is it added to CHANGES.rst? If you want to avoid merge conflicts,
  list the proposed change log here for review and add to CHANGES.rst before merge. If no, maintainer
  should add a no-changelog-entry-needed label.

Checklist for package maintainer(s)

This checklist is meant to remind the package maintainer(s) who will review this pull request of some common things to look for. This list is not exhaustive.

• Are two approvals required? Branch protection rule does not check for the second approval. If a second approval is not necessary, please apply the trivial label.
• Do the proposed changes actually accomplish desired goals? Also manually run the affected example notebooks, if necessary.
• Do the proposed changes follow the STScI Style Guides?
• Are tests added/updated as required? If so, do they follow the STScI Style Guides?
• Are docs added/updated as required? If so, do they follow the STScI Style Guides?
• Did the CI pass? If not, are the failures related?
• Is a milestone set? Set this to bugfix milestone if this is a bug fix and needs to be released ASAP; otherwise, set this to the next major release milestone.
• After merge, any internal documentations need updating (e.g., JIRA, Innerspace)?

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (9414cd8) 90.85% compared to head (27efa68) 90.86%.

Files	Patch %	Lines
jdaviz/app.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2677   +/-   ##
=======================================
  Coverage   90.85%   90.86%           
=======================================
  Files         162      162           
  Lines       21126    21127    +1     
=======================================
+ Hits        19195    19196    +1     
  Misses       1931     1931           

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[pllim]

Looks reasonable. Thanks!

[pllim]

I'll let you decide if you also want Brett to review. If not, feel free to merge.

[kecnry]

I did try to generalize this logic instead of hardcoding the config, but not sure its worth it until/unless other configs need this logic? See the commit history to see a failed attempt.

[bmorris3]

Sensible. Thanks!