add heltec v4.3 board

[Quency-D]

1. This is the schematic diagram for v4.3.
2. The main difference between v4.2 and v4.3 is the different fem and the different control pins of the fem.
3. You can identify whether it is v4.2 or v4.3 by the default pull-up and pull-down resistors of GPIO2.
4. The fem control code is centralized into a single file.

[Quency-D]

Hi @weebl2000, I've tested and organized it, and I still think it's simpler to separate the fem control into a separate file. Do you have any other suggestions?

[weebl2000]

Hi @weebl2000, I've tested and organized it, and I still think it's simpler to separate the fem control into a separate file. Do you have any other suggestions?

Make sure the FEM keeps power when it's enabled and the ESP32 is sleeping. See also PR #1600, it's not merged to dev yet.

Other than that go for it. Let me know if I can help out reviewing!