feat: wip on fpbase spectra viewer

[tlambert03]

very wip to add a spectra viewer that pulls data from fpbase. fpbase code is borrowed from microvis (could be put in separate package), and plot widget is same code as being used in ndv histogram PR.

from vispy import app

from pymmcore_widgets.views._spectra_viewer import SpectraViewer

widget = SpectraViewer()
widget.add_spectrum("mTurquoise")
widget.add_spectrum("mStayGold")
widget.add_spectrum("mCherry")
widget.add_spectrum("Chroma ET525/50m")
app.run()

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 155 lines in your changes missing coverage. Please review.

Project coverage is 89.22%. Comparing base (1cda2b7) to head (c675e80).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/pymmcore_widgets/_vispy_plot.py	0.00%	132 Missing ⚠️
src/pymmcore_widgets/views/_spectra_viewer.py	0.00%	23 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #388      +/-   ##
==========================================
- Coverage   90.71%   89.22%   -1.50%     
==========================================
  Files          85       87       +2     
  Lines        9234     9389     +155     
==========================================
  Hits         8377     8377              
- Misses        857     1012     +155     

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