add distinct extractor route

[adelavega]

Closes #923 + adds a route for it. This would help in documentation as well

[codecov-commenter]

Codecov Report

Merging #931 (10b46ff) into master (f1b2f72) will decrease coverage by 0.43%.
The diff coverage is 35.71%.

@@            Coverage Diff             @@
##           master     #931      +/-   ##
==========================================
- Coverage   83.14%   82.71%   -0.44%     
==========================================
  Files          62       63       +1     
  Lines        3103     3129      +26     
==========================================
+ Hits         2580     2588       +8     
- Misses        523      541      +18     

Impacted Files	Coverage Δ
neuroscout/core.py	67.74% <ø> (ø)
neuroscout/utils/misc.py	11.76% <11.76%> (ø)
neuroscout/resources/extractor.py	84.37% <70.00%> (-6.93%)	⬇️
neuroscout/resources/__init__.py	100.00% <100.00%> (ø)

---

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[cypress]

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Test summary

0 • 7 • 0 • 0

---

Run details

Project	Neuroscout
Status	Failed
Commit	8fbc351 ℹ️
Started	May 6, 2021 10:44 PM
Ended	May 6, 2021 10:45 PM
Duration	00:41 💡
OS	Linux Ubuntu - 20.04
Browser	Electron 87

View run in Cypress Dashboard ➡️

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Failures

	analysis_builder.spec.js		1
1	Analysis Builder > analysis builder
	home_spec.js		6
1	The Home Page > successfully loads
2	The Home Page > navigation bar contents
3	The Home Page > splash page contents
4	The Home Page > test sign up button 1
5	The Home Page > test sign up button 2
6	The Home Page > test sign in button

---

This comment has been generated by cypress-bot as a result of this project's GitHub integration settings. You can manage this integration in this project's settings in the Cypress Dashboard

[cypress]

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Test summary

0 • 7 • 0 • 0

---

Run details

Project	Neuroscout
Status	Failed
Commit	10b46ff
Started	May 6, 2021 10:45 PM
Ended	May 6, 2021 10:45 PM
Duration	00:52 💡
OS	Linux Ubuntu - 20.04
Browser	Electron 87

View run in Cypress Dashboard ➡️

---

Failures

	analysis_builder.spec.js		1
1	Analysis Builder > analysis builder
	home_spec.js		6
1	The Home Page > successfully loads
2	The Home Page > navigation bar contents
3	The Home Page > splash page contents
4	The Home Page > test sign up button 1
5	The Home Page > test sign up button 2
6	The Home Page > test sign in button

---

This comment has been generated by cypress-bot as a result of this project's GitHub integration settings. You can manage this integration in this project's settings in the Cypress Dashboard