TPF viewer: marker/mouseover support

[kecnry]

This PR adds full mouseover information and marker plugin support for the TPF viewer.

[codecov]

Codecov Report

Attention: Patch coverage is 68.75000% with 20 lines in your changes missing coverage. Please review.

Project coverage is 92.18%. Comparing base (7b78df5) to head (b41fbca).
Report is 33 commits behind head on main.

Files with missing lines	Patch %	Lines
lcviz/plugins/coords_info/coords_info.py	68.25%	20 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #104      +/-   ##
==========================================
- Coverage   93.92%   92.18%   -1.75%     
==========================================
  Files          37       39       +2     
  Lines        1598     1945     +347     
==========================================
+ Hits         1501     1793     +292     
- Misses         97      152      +55     

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[bmorris3]

This works great for me with jdaviz==3.9.0.

One important thing: when you run

markers = lcviz.plugins['Markers']
markers.export_table()

you get a table with the times in the dt units. Let's transform those to proper JD/MJD before export:

[bmorris3]

And to be clear – I have approved so we can merge once we add units or decide to do that later, fix the time column in the exported marker table, and tests pass.

[kecnry]

Added the time unit - good catch.

I'm a bit conflicted on the handling of reference time to get back to JD, etc. If the x-axes and mouseover show dt, then I think it makes sense for that to be maintained during export. But maybe we could/should include the reference time in the table as well? Or maybe we just really need to think about reference time in general and have its behavior configured in a plugin (this is on our roadmap 🐱, but we haven't really fleshed out what that would look like yet). Thoughts? Maybe we should defer that for now and link back to this discussion for when we take on that effort?