klipper-flash: rewrite flasher script

This completely removes gcc/make from the update loop, and fixes it for
at least some boards.

Although only tested on some boards, and probably lacking support
for some, that's vastly better than sending avr-gcc to your RPi every
update, and not working afterwards.

This also introduces makeFlasher in firmware passthroughs. Use it like
so:
```
  firmware = klipper-firmware.override {
    mcu = "myprinter";
    firmwareConfig = ./config;
  };
  flasher = firmware.makeFlasher {
    flashDevice = "/dev/ttyACM0";
  };
```

0 files changed, 0 insertions, 0 deletions