add c3 diversity pa json

[LYNHQQ]

Providing a Diversity PA setup for the ESP32-C3, allowing it to perform automatic antenna switching.

[JyeSmith]

Could you also add a target to the 'targets.json' file. Something similar to c3-plain-pa should be fine.

[LYNHQQ]

您能否也向 'targets.json' 文件添加一个目标。类似于 c3-plain-pa 的东西应该没问题。

Of course, but I think it should be like the Generic 2400 Diversity PA. In this way, C3 also has the function of Diversity PA.