[Feature] switch userapps to smart-build

[unicornx]

Describe problem solved by the proposed feature

https://github.com/RT-Thread/smart-build

这个应该可以完全替代之前的userapps，或者后续userapps未来专注于放一个个应用的repo
应该是可以替代了，但需要多用。目前应该是把userapps里的脚本整体又包进来了吧，类似于userapps的超集

目前在 RTT 侧使用 RT-Thread#9623 跟踪此项工作。

Describe your preferred solution

No response

Describe possible alternatives

No response