[ie/theatercomplextown] Add extractors

[bashonly]

theater-complex.town is a subscription/PPV service that streams Japanese theater productions. Its web API is identical to that of StaCommu, another Japanese subscription-based streaming service.
(The G Play store says that both sites' Android apps are developed by "CyberAgent Inc.", which is likely the same company as "CyberFight Inc." that develops the Wrestle-Universe app.)

Because of the carbon copy API, I didn't have to do much here: just moved some methods to the Stacommu baseclass and plugged in a different API key and hostname

Closes #8491

Template

Before submitting a pull request make sure you have:

• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests

In order to be accepted and merged into yt-dlp each piece of code must be in public domain or released under Unlicense. Check all of the following options that apply:

• I am the original author of this code and I am willing to release it under Unlicense
• I am not the original author of this code but it is in public domain or released under Unlicense (provide reliable evidence)

What is the purpose of your pull request?

• Fix or improvement to an extractor (Make sure to add/update tests)
• New extractor (Piracy websites will not be accepted)
• Core bug fix/improvement
• New feature (It is strongly recommended to open an issue first)

Copilot Summary

🤖 Generated by Copilot at f7dbeb7

Summary

🎭🎬♻️

Refactor and add extractors for stacommu and theater-complex.town. The change improves the code structure and reusability of the stacommu extractors and adds support for a new site that offers theater streaming. The change affects the files yt_dlp/extractor/stacommu.py, yt_dlp/extractor/theatercomplextown.py, and yt_dlp/extractor/_extractors.py.

Oh we are the coders of yt-dlp
We scrape the sites for video clips
We add new extractors to the list
And refactor the old ones with a twist

Walkthrough

• Add support for theater-complex.town, a Japanese platform for streaming theater performances, by creating two new extractor classes: TheaterComplexTownVODIE for video on demand content and TheaterComplexTownPPVIE for pay-per-view content (link)
• Move the base class StacommuBaseIE from yt_dlp/extractor/stacommu.py to yt_dlp/extractor/_extractors.py to avoid circular imports and enable inheritance by the new classes (link)
• Simplify the extraction of video on demand content from stacommu.jp by calling the _extract_vod method of StacommuBaseIE in the _real_extract method of StacommuVODIE (link)
• Simplify the extraction of pay-per-view content from stacommu.jp by calling the _extract_ppv method of StacommuBaseIE in the _real_extract method of StacommuLiveIE (link)