[Build] Set ETH enabled for all IDF 5.1 builds

[tonhuisman]

Features:

• Enable Ethernet support (_ETH) for all IDF 5.1 builds, and disable/remove duplicates
• Add ESP32-C3 Energy LittleFS ETH build

TODO:

• Testing
• Check/update documentation

[iz8mbw]

So if I need to build a Custom build for my ESP32 and I want to use LittleFS should I select the one with Ethernet also if I don't use Ethernet?

[tonhuisman]

So if I need to build a Custom build for my ESP32 and I want to use LittleFS should I select the one with Ethernet also if I don't use Ethernet?

For a Custom build you can still decide the plugins and features included, I've only enabled this to increase the nr. of ETH builds, without increasing the total number of builds.
Having Ethernet included shouldn't make any difference in the functioning, until you enable Eth. Then you should have some ethernet device connected 😉