rebase the demos of the dev branch to the trunk branch

[TangMeng12]

Note: Please adhere to Contributing Guidelines.

Summary

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what it exactly does and how, if new feature shows up, provide
references (dependencies, similar problems and solutions), etc.

Impact

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build process, hardware, documentation, security, compatibility, etc.

Testing

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what Host was used for build (OS, CPU, compiler, ..), what Target was
used for verification (arch, board:config, ..), etc. Providing build
and runtime logs from before and after change is highly appreciated.