[SnapchatStory] Add new extractor

[Tatsh]

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What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

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Description of your pull request and other information

Add new extractor for Snapchat stories in the web player.

[sdushantha]

Would it be possible to add support to map.snapchat.com links?

You can take a look at this repo which supports this type of link.
https://github.com/notcammy/PySnapStories/blob/master/pysnapstories.py

[Tatsh]

I added support for those links. The test uses State College, Pennsylvania.

[Tatsh]

@dstftw Please review again since the last commit.

[Tatsh]

Bump

[Tatsh]

@dstftw If you want me to make changes, I'll need to re-make this PR. I asked GitHub and they cannot fix branch references.