Mark FFmpeg integration as system type

[frenck]

Proposed change

During the beta, ffmpeg came up a couple of times, as it is now listed on the integration dashboard. It is always pulled in via as a dependency.

While there is a YAML configuration available for this integration, it only denotes the location of the ffmpeg binary. It will never create cameras, other integrations will rely on this ffmpeg integration instead.

Therefore, it makes more sense (and cause less confusion) to mark this integration a "system" type of integration.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
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