Update Directions In TUTORIAL.md; Add Unit Tests To non_user_endpoints test.py (#1136)

* Update navigational directions in Step 1(A)

* Combine directions in Step 1(B) and Step 2(C) and remove Step 2(C)

* Update navigational directions and verbage in Step 1(C)

* Change reference from Step 1(C) to Step 1(B) in Step 2(D)

* Update capitalization in Prerequisites Step 3

* Add directions for installing Spotipy in Prerequisites Step 1(A)

* List updates to TUTORIAL.md file in CHANGELOG.md

* Update docstrings for funcs in lines 340-585

* Add unit tests for artist ID and URL

* Add test_artists_mixed_ids

* Updated CHANGELOG.md and TUTORIAL.md as requested

* Update client.py and test.py

* Fix linting issue

* Remove duplicate line; Change order of prerequisites

* Update local repo

* Add test_artists_mixed_ids

* Add Radiohead ID and URL; Add qotsa URL

* Add test_artist_url

* Comment out three failing tests

* Fix linting errors

* Uncommenting out failed tests

* Add test_artist_id

* List changes in CHANGELOG.md

* Add line breaks at the end of files.

* Remove multiple spaces

Also I've removed a sentence that just doesn't make sense in my eyes, but was added before this PR.

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Co-authored-by: Niko <github@dieserniko.link>

CONTRIBUTING.md

@@ -68,3 +68,4 @@ Don't forget to add a short description of your change in the [CHANGELOG](CHANGE
  - Create github release https://github.com/plamere/spotipy/releases with the changelog content
    for the version and a short name that describes the main addition
  - Verify doc uses latest https://readthedocs.org/projects/spotipy/
+