Add cmap option to specify the colormap of plot

[yuyizheng1112]

This PR aims to allow the user to set specific color scale in the plot.
This should be merged after restructuring (#1777). Please see the changes in commit 2bc2e69.

Description

• Add cmap option to display() method - It requires a string to specify the name of the color map. The default color scale is 'jet'.
• Add plot_cmap attribute to widget class because the colormap string is also used in add element method.
• Add docstrings for new attributes.

Examples

Default color scale:

Custom color scale:

Type of change

• Bug fix.
• New feature.
• Breaking change.
• None of the above.

Checklist

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
  • (optional) I have built the documentation on my fork following the instructions.
• I have assigned and requested two reviewers for this pull request.

[tardis-bot]

Before a pull request is accepted, it must meet the following criteria:

• Is the necessary information provided?
• Is this a duplicate PR?
  • If a new PR is clearly a duplicate, ask how this PR is different from the original PR?
  • If this PR is about to be merged, close the original PR with a link to this new PR that solved the issue.
• Does it pass existing tests and are new tests provided if required?
  • The test coverage should not decrease, and for new features should be close to 100%.
• Is the code tidy?
  • No unnecessary print lines or code comments.

[codecov]

Codecov Report

Merging #1788 (4b16138) into master (fa42fbc) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1788      +/-   ##
==========================================
- Coverage   58.38%   58.34%   -0.05%     
==========================================
  Files          66       66              
  Lines        6705     6712       +7     
==========================================
+ Hits         3915     3916       +1     
- Misses       2790     2796       +6     

Impacted Files	Coverage Δ
...s/tardis/visualization/widgets/custom_abundance.py	14.42% <0.00%> (-0.01%)	⬇️

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[sourcery-ai]

Sourcery Code Quality Report

✅  Merging this PR will increase code quality in the affected files by 0.44%.

Quality metrics	Before	After	Change
Complexity	3.85 ⭐	3.74 ⭐	-0.11 👍
Method Length	83.54 🙂	81.68 🙂	-1.86 👍
Working memory	9.83 🙂	9.76 🙂	-0.07 👍
Quality	63.30% 🙂	63.74% 🙂	0.44% 👍

Other metrics	Before	After	Change
Lines	1613	1642	29

Changed files	Quality Before	Quality After	Quality Change
tardis/visualization/widgets/custom_abundance.py	63.30% 🙂	63.74% 🙂	0.44% 👍

Here are some functions in these files that still need a tune-up:

File	Function	Complexity	Length	Working Memory	Quality	Recommendation
tardis/visualization/widgets/custom_abundance.py	CustomAbundanceWidgetData.from_csvy	12 🙂	413 ⛔	18 ⛔	28.54% 😞	Try splitting into smaller methods. Extract out complex expressions
tardis/visualization/widgets/custom_abundance.py	CustomAbundanceWidget.on_btn_add_shell	14 🙂	383 ⛔	11 😞	36.17% 😞	Try splitting into smaller methods. Extract out complex expressions
tardis/visualization/widgets/custom_abundance.py	CustomAbundanceWidget.create_widgets	1 ⭐	537 ⛔	13 😞	43.87% 😞	Try splitting into smaller methods. Extract out complex expressions
tardis/visualization/widgets/custom_abundance.py	CustomAbundanceWidget.generate_abundance_density_plot	1 ⭐	191 😞	16 ⛔	49.11% 😞	Try splitting into smaller methods. Extract out complex expressions
tardis/visualization/widgets/custom_abundance.py	DensityEditor.create_widgets	0 ⭐	302 ⛔	12 😞	49.51% 😞	Try splitting into smaller methods. Extract out complex expressions

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• ⛔ very poor

The 👍 and 👎 indicate whether the quality has improved or gotten worse with this pull request.

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