Add a board config to 'Board Explorer' for standalone 328P PU (DIP28 IC on breadboard) with 8MHz and 1MHz internal clock

[crunchysteve]

'Board Explorer' needs a standalone config for 328P PU (DIP28 IC on breadboard) with 8MHz and 1MHz internal clock.

I've tried to generate one from the docs but that low-level stuff just breaks my brain as well as breaking a few ICs in my attempts. Even pros would benefit from having such a setup in the Board Explorer. Being able to copy paste the default setup is a productivity aid. I have a project I can't progress in PlatformIO and will need to regress to ArduinoIDE without a naked chip board config for the 328P PU.

Cheers, Crunchy, Melbourne Australia