[Zephyr]selecting a runner

[stc1988]

I am trying to run a Pico on Zephyr, but the default runner is set to openocd, but I think that using uf2 would make it possible to flash it.

I think it would be convenient if we could define something like zephyrRunner in manifest.json.

[phoddie]

Interesting suggestion. I suppose that would go in the manifest for the specific device? Alternatively it could go on the mcconfig command line.

[stc1988]

Since runner is Zephyr-specific, I think it’s fine for it to be in the manifest like zephyrShields.