[bandlab] add extractor (supersedes #31206) (Closes #31184)

[aiur-adept]

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• Searched the bugtracker for similar pull requests
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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

Bandlab extractor for individual posts, albums, and collections

Closes #31184

[aiur-adept]

This is a continuation of #31206

[aiur-adept]

@dirkf I think this can merge now

[dirkf]

You can put (eg) Supersedes, closes #31206 in the PR description to have that PR closed automatically when this is merged.