Generic x86 64

[jens-maus]

Description

This PR renames the intelnuc platform to generic-x86_64 to signal its more general nature to a generic x86_64 drives platform implementation for RaspberryMatic. In addition, it also changes from Legacy Boot/BIOS to (U)EFI boot similar to generic-arm64 already is.

However, please note that this means that with the next version users which previously used the intelnuc platform images would have to completly reinstall the generic-x86_64 on their hardware (e.g. IntelNUC) and then restore a latest backup to get back working. However, this should be quiet easily doable given the positive effects of that very change. In addition, by calling it `generic-x86_64´ it should be more clear to new users that these kind of images could be in principle installed on any ordinary modern x86_64 based hardware.

Related Issue

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Types of changes

• [ ] Docs change / refactoring / dependency upgrade
• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [X] Breaking change (fix or feature that would cause existing functionality to change)

Alternate Designs

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Possible Drawbacks

User have to be notified and documentation still be changes to make it clear that this essential a fresh install that needs to be performed.

Verification Process

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Release Notes

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Contributing checklist

• [X] My code follows the code style of this project.
• [X] I have read the CONTRIBUTING and LICENSE document.
• [X] I fully agree to distribute my changes under Apache 2.0 license.