Fixing configuration migration issues

[Lord-Grey]

Summary

Fix - Correct JSON processing
Fix - Show effectsconfigurator menu entry, only if effectengine is available

Improvements

• JSON getconfig API - allow filter to exclude elements via "null"
• Update schemas to accept empty arrays
• Stop WebServer before JSON API to avoid blocking calls by UI

hyperion.ng/commit/dbfc59a28c09ff3bd91fca81d588c1d0a1bba725)

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• Bugfix
• Feature
• Code style update
• Refactor
• [] Docs
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If changing the UI of web configuration, please provide the before/after screenshot:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing setups:

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's body (e.g. Fixes: #xxx[,#xxx], where "xxx" is the issue number)

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• Related documents have been updated (docs/docs/en)
• Related tests have been updated

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• Yes, CHANGELOG.md is also updated

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