[verystream] Add new extractor (is just a copy of Openload with little changes)

[ghost]

Before submitting a pull request make sure you have:

• At least skimmed through adding new extractor tutorial and youtube-dl coding conventions sections
• Searched the bugtracker for similar pull requests
• Checked the code with flake8

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What is the purpose of your pull request?

• Bug fix
• Improvement
• [X ] New extractor
• New feature

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Description of your pull request and other information

It's just a copy of Openload with some adjustment for new site.

[ghost]

for issue #20701

[ealgase]

Hey @remitamine, can you please take a look at this?

[remitamine]

obviously, duplicating the whole extractor just because the two websites differ slightly in the URLs is not acceptable.

[ealgase]

Ah, so verystream should be added to the openload extractor?

[ealgase]

I've now added support for verystream.com to the openload extractor (#20967).