Add line info widget to TARDIS: demo notebook

[jaladh-singhal]

This PR aims to share a notebook for experimentation and code that will be used to create line info widgets.

NOTE: This is not intended for merging.

Motivation and Context

This a part of GUI project to create line info widget for TARDIS.

How Has This Been Tested?

All the code in notebook works fine by executing cells.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

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Codecov Report

Merging #1187 into master will increase coverage by 2.90%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1187      +/-   ##
==========================================
+ Coverage   77.73%   80.63%   +2.90%     
==========================================
  Files          92       41      -51     
  Lines        5731     3424    -2307     
==========================================
- Hits         4455     2761    -1694     
+ Misses       1276      663     -613     

Impacted Files	Coverage Δ
tardis/io/util.py	73.56% <0.00%> (ø)
tardis/io/decay.py	89.65% <0.00%> (ø)
tardis/util/base.py	77.77% <0.00%> (ø)
tardis/plasma/base.py	58.27% <0.00%> (ø)
tardis/widgets/base.py	93.85% <0.00%> (ø)
tardis/io/model_reader.py	97.70% <0.00%> (ø)
tardis/io/parsers/csvy.py	89.74% <0.00%> (ø)
tardis/io/atom_data/base.py	91.17% <0.00%> (ø)
tardis/io/atom_data/util.py	47.05% <0.00%> (ø)
tardis/io/parsers/stella.py	0.00% <0.00%> (ø)
... and 77 more

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[wkerzendorf]

@jaladh-singhal is this still relevant

[jaladh-singhal]

This PR is no longer relevant since line-info-widget has already been pushed under #1264 so closing it for now.

The notebook in this PR will be useful in future though to check out prototypes and other possible options we can use to add more features in Line Info Widget.