Integrate seco-base/kirkstone_next_2_0

Commit: https://git.seco.com/edgehog/seco-base/-/commit/421b4c95b0e6ec9af29f6fca9402cacde7ef983b

[FOLDERS][MTK] move meta-seco-mtk to meta-seco folder

Move meta-seco-mtk to meta-seco/ as done for the other meta-seco-* layers.

Original commit message: All meta-seco-* layers have been placed inside meta-seco folder. In this way is easier to highlight the code base which composes and characterizes the Edgehog OS distro. All other layers from the third part have been leaved in the same layer as others.

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Commit: https://git.seco.com/edgehog/seco-base/-/commit/1c46b8077017d6803d03e4c06fbc2c8a7eba3476

[QEMU] add support for qemux86 and qemux86-64

Add Yconfig and defconfig files for qemux86 and qemux86-64 (q35) boards

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Commit: https://git.seco.com/edgehog/seco-base/-/commit/687d9b4cd607968b508057a65a186f6264ea8913

[QEMU] add support for qemuarm and qemuarm64

Add Yconfig and defconfig files for qemuarm and qemuarm64

(QEMU virt machine ARMv7/8 with poky BSP layer)

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Commit: https://git.seco.com/edgehog/seco-base/-/commit/618f18f57135510d7f22f6825bfc5b4440ff691d

[FOLDERS] Place all SECO layers inside meta-seco root folder

All meta-seco-* layers have been placed inside meta-seco folder. In this way is easier to highlight the code base which composes and characterizes the Edgehog OS distro. All other layers from the third part have been leaved in the same layer as others.

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Commit: https://git.seco.com/edgehog/seco-base/-/commit/56e0cb64b44bde906ebcdec918f0286dbda10fc5

[RPI] add support for the raspberrypi 4

Add defconfig and Yconfig files to build Edgehog for the raspberrypi 4